This amp challenged everything I thought I knew! xDuoo TA-66 review

[@bgav]

I just got my TA-66 yesterday from Apos. It's my first headphone tube amp. I'm loving it so far paired with HD650s, fed by the DAC in my Shanling EC3. The stock tubes sound great, and they aren't even close to being burned in yet, good soundstage, punchy, tight bass, warm midrange. Male and female vocals both sound excellent. I'm hooked.

[@PassionforSound]

I'm so glad you're enjoying it! Congratulations and happy listening!

[@bgav]

@@PassionforSound thanks your review helped me decide to pull the trigger on it!

[@PassionforSound]

@bgav awesome! So glad I could help

[@nunoferraz5426]

A Quality delivery.... always a pleasure hearing your review. Secondly, you are being faithful to the hobby by reviewing different price points. Well done.

[@PassionforSound]

I'm glad you liked it. I find there's great enjoyment at all budget levels so I try to share anything I can get my hands on that I think is interesting in some way.

[@ishaajo2715]

Thanks Loquah.

[@rbhis000]

I know it was only a minor gripe, but there is a great reason for the power switch being on the back. I do that on my builds to keep power away from the audio signal. It’s a little inconvenient, but makes the rest of the build so much easier.

[@PassionforSound]

I can understand that. I'm sure there could be creative workarounds though...

[@Nephilim-81]

Lachlan. I love how you are finding value in HIFI at all price points. Well done. ❤.

[@PassionforSound]

There's so much great gear at every level (and some duds too) so it's fun trying it all out

[@mariaborkowska1988]

@@PassionforSound Hi Lachlan. When will you post a review of the XDuoo TA-66 with the 6N2P EW Voskhod tube? (EW means military purpose) Did you allready receive this bulb? Greetings from Poland Leszek

[@PassionforSound]

I still haven't received the tube! I got a call from the post office the other day though so perhaps it's there...

[@mariaborkowska1988]

@@PassionforSound I got it. So I'm still waiting....

[@PassionforSound]

Yeah, it's been returned to sender. The seller is sending a new one now...

[@russellnedland4569]

I ended up with that “Russian rocket” tube in the front and a Svetlana winged C in the back. Pretty magical.

[@BillyKueekSG]

Great review, again! I still have the original TA-26, just find that having the on/off switch in front for a tube amp makes more sense. The 6N8P replacements are easier. I have the Sylvania 6SN7GT, Ken-Rad 6SN7GTA, GE 6SN7, a Soviet OTK 6SN7 and my favorite being the Tungsol 6SN7GT Mouse Ears. I find it hard to get more options or better replacement for the 6N5P, only managed to get a Soviet Union 6H5C/6080, GE 6AS7 and Thomson-CSF 6080WA and none really delights me yet. I can so resonate with your statement “some nights everything just sounds amazing”, glad I am not alone. Any recommendations for the 6N5P replacement?

[@PassionforSound]

I really like my Tung Sol 6AS7G

[@MatthewDiFazio]

Love this! I’m a huge TA-66 fan myself, and am so happy with the recognition it’s getting. Thanks for the review, Lachlan. Have you tried the TA-22? It’s another fantastic product from xDuoo!

[@PassionforSound]

I haven't tried the TA-22, but I love most of their products. Whoever designs their gear is/are very talented.

[@dragonfire61]

Just got my ta-66 yesterday. Using a Voskod 6n2p-EB and a Winged "C" 6H13C power tube. Sound quality is nothing short of amazing.

[@PassionforSound]

Awesome! So glad you're enjoying it

[@brianliu522]

How has the sound changed after you replaced the small stock tube with the Voskhod 6n2p-EV ? Thanks

[@Artemis_Prix]

Hi Lachlan, absolutely thrilled to see you caption Tash Sultana on your channel! She is an incredible artist and her music is mesmerizing. Her Tiny Desk concert is truly amazing because you get to see a master at the top of her craft.

[@PassionforSound]

Ooh! I'll definitely check out her Tiny Desk gig. Thank you!

[@josephpino07]

Hi. Thanks for the wonderful review. Does this amp have any sort of gain? The specs sheet says "gain +18". I am not sure what that means. Thank you.

[@PassionforSound]

That just means it amplifies the incoming voltage by 18dB which is fairly significant - it's just a touch less than doubling the loudness of the incoming signal.

[@SuperSeltzer]

There are lots of tube choices if you like to use the adapter. Any 5751 and 12AX7 would do nicely w/ adapter.

[@spamcan9208]

Wow, having point-to-point wiring that also doesn't look like absolute dog sh!t is a nice surprise. I wasn't expecting that at all. And I'm glad they decided to not chase power numbers. I really like the updated look but I still don't get why they kept that power switch on the back after all the attention to detail. Regardless it's a very nice unit.

[@CJDilag]

Enjoyed this one as always, Lachlan! Got my TA-66 a couple of days ago and on sale. Eagerly waiting for its arrival.

[@PassionforSound]

Awesome! I hope you love it as much as I do.

[@tonythearchitect]

Great review and I'm very tempted to get one but I already have a bottlehead crack w/speedball. Curious to know how these two compare either if you have the speedball or maybe from memory. I know my speedball, for iems, is better than my Aune S17 Pro. Thanks!

[@PassionforSound]

I don't have a Crack anymore, but having built a few of them in the past, including upgrading caps, etc. I'm pretty confident that the Crack is the better amp still. Enjoy what you have. 🙂

[@tonythearchitect]

@@PassionforSound Thanks. I hear from Wave Theory that the bottlehead crack has more resolution.

[@PassionforSound]

@tonythearchitect that makes sense

[@ancientalien815]

Your mic sounds really good in this video.

[@PassionforSound]

Thanks for letting me know. I've been tinkering with mic placement and think I've got it almost perfect now... 🙂

[@andrewgiovannini6613]

In an interview Rob Watts mentioned that the licensing cost to use the 4.4 connector was very high and cited it as the reason for not including it in the Mojo 2 to stay within their target for pricing. I wonder if the cost reduction mostly came from not including it on the TA 66. Nice review as always!

[@PassionforSound]

That's a good point. It's not what's happening here though because the TA-26 had no 4.4mm either and still cost $70 more.

[@MeteoraEra]

So it makes the zmf Verite to show some of its potential and have more wet/ liquid sounding? on any SS amp, VC's decays are way too quick and dry and boring.. I've been hesitating between getting ta-66 or Aune s17 pro for VC closed to have it sound a bit less dry and more enjoyable, maybe more liquid sounding. My previous amps are Singxer sa1, MOJO 2, RU6, and VC sounded very much dry on all of them. 1. Do you think this would make them more pleasant and liquid sounding?. 2. Or you would recommend Aune s17 as a better option? (But it'd be more dry and boring sounding?) For reference, I prefer liquid ~ planar like sounds but I'm stuck with my VC. Thank you, big fan of your work.

[@PassionforSound]

If you want slightly slower feeling transients and a more liquid sound, definitely go for tubes and this is an excellent option.

[@Alextraz]

Is this a good combo with Sivga P2 pro you have recently reviewed. I felt that those headphones ...at least the way you have described them...might be goos fit for me.

[@PassionforSound]

I would probably choose a good solid state amp for the P2 Pro. They don't really need extra smoothness or warmth. The TA-66 isn't overly rich, but still might not be the best fit with the Sivgas. I'd look at a decent amp from Schiit or Geshelli Labs first. Perhaps a Topping or SMSL option if you're somewhere that's hard to get the USA brands.

[@Alextraz]

@@PassionforSound in that case wonti be ok with my main amp - atoll in200se?

[@PassionforSound]

I don't know that one, but if it's a regular solid state amp it should be great

[@MichaelBrown-oo1ym]

Nice review. You helped me decide on both TA66 and Burson Voyager deluxe . Right now I have ZMF Atrium, HE1000SE and JM Audio modded closed Hifiman. Looking forward to your follow up review of the Burson Voyager with the new power supply

[@PassionforSound]

Great collection! Glad I could help. I hope to have the new power supply and the new Conductor GT4, and Timekeeper Voyagers coming soon...

[@subcoded]

Very nice review! I own HD650 but I don't like them (i find them boring sounding with bad soundstage) Do you think that this amp will drive AKG K701s that i'm planning to buy?

[@PassionforSound]

It should be fine with those

[@baycchief3785]

Awesome review. I'm a new subscriber and hope to learn a lot from you. Quick question, for a great headphone DAC, would you recommend the Fiio K11 R2R or to get the best out of this tube amp, what would you recommend? I like the K11 R2R tech and I'm curious what would bring the best out of this TA-66 if there is still room to improve if at all. TY

[@PassionforSound]

I'm yet to try the K11 (but I have one here). I suspect the TA-66 might be capable of performing even better than the K11 can provide, but it should be a great starting point.

[@JošJedan-j2y]

​I'm interested in this as well. I'm waiting for a recommendation for a new DAC (currently I'm using SMsL SU-1) . Thanks​@@PassionforSound

[@davidmolyneux9014]

That's a great little DAC, you may struggle to better its performance. The K11 R2R also had a really good DAC, if you want a great value all-in-one with amp. It won't sound any different to the SU1 but it will give you amp, se and balanced jacks, digital display and RCA out / preamp option, if you later add a separate amp. It doesn't have EQ though, which I use with my headphones. You could just add a Wiim mini for the EQ and streaming and be done (assuming you already have an amp). So many great options out there, have fun with whatever you choose!

[@russellnedland4569]

This with a pair of Senn 6XX ROCKS!!! As far as tube rolling, you might gain soundstage, but tonaly it’s pretty good.

[@PassionforSound]

I agree. It's really only staging I was wanting to tweak 🙂

[@mtinhk]

Amazing review. Most tempted to get one to replace my Fosi P3. Got an HE-R9 in the past after listening to your review. Most happy with it. That was a brave one.

[@PassionforSound]

I'm glad I could help here and with the R9. The TA-66 is definitely a really solid choice IMO.

[@brianliu522]

Thanks for the wonderful review. I got my TA-66 two days ago and I have listened with HD800s for about 10 hours total with the stock tubes for classical music. It is my first OTL tube amp and I am still learning about the new experience. While I still enjoy the sound, I find that the clarity/detail is somewhat lacking as it has more emphasis on the bass compared to the hybrid Xduoo MT-604 that I have. My question is how I can alter the sound signature slightly by tube rolling to make a bass a bit tighter and increase the treble? Should I try replacing the pre-am (the small) tube first? If yes, what model should I consider? Thank you very much and greetings from Canada!

[@PassionforSound]

Hi Brian, what you're hearing is a very normal character of pure tube amps compared to solid state or hybrid designs. The good news is that both tubes influence what you're hearing so it's worth playing with both. The best bet is to check some reviews for the tubes that can go in each socket, but the power socket (the larger, back tube) has more options available so probably start there with something like a new production Tung Sol 6AS7G like the one I'm using as it's affordable and sounds great.

[@brianliu522]

@@PassionforSound thank you so much. Appreciate it

[@Andrew-cp7mc]

@@PassionforSound Thanks for a great review. I have ordered it based on yours and another review. What is the sonic difference between the stock power tube and Tung Sol 6AS7G? Is this tube readily available in Australia as I cant seem to find it online from a quick search. I am currently using my HD800s on my Asgaard 3 and want to try an OTL for the first time. I previously had a Schiit Vali 2+ which was very close to the Asgaard 3 to my ears.

[@PassionforSound]

@Andrew-cp7mc I think I bought the 6AS7G here in Australia as new production stock, but it's been a while. If you can get it, it's a little more resolving and spacious, but otherwise not a big tonal shift. Generally, any quality 6AS7 equivalent should work well and be a nice upgrade from the stock tube.

[@brianliu522]

@@PassionforSound A quick update: After listening to my TA-66 for about 15 hours during the last 2 weeks, I found that the sound opened up with more clarity than before. Very happy with the result. BTW, I just ordered a 6N2P-EV Voskhod tube and winged C 6H13C Svetlana tube. Hope to receive them soon.

[@OzSteve]

Great review. I ordered one of these last week and waiting on it to arrive. I have the 26 and 26s (and a few others from Xduoo) Be interested in the replacement from tube when you get your box.

[@PassionforSound]

I hope you enjoy the 66! I'll try to do a short video or community post when the tube arrives. 🙂

[@OzSteve]

@@PassionforSound I'm really looking forward to the TA-32. I wonder how much better it'll be over the TA-22. I'll be pre-ordering it when I see it advertised

[@TheRedMantra]

The 6N5PJ tube can still be rolled. 6AS7G, 6080, 7236, 7802, 5998/421a. Lots of good options from $20-60 USD. Of course some of the ones I mentioned can cost a fortune relative to the cost of the amp, but good tires can make a mid level bicycle ride noticeably better.

[@ropeburn6684]

Personally, I prefer to carefully exchange my electronic parts, especially fragile ones such a tubes. Wouldn't want them rolling off the table.

[@datdudeinred]

Lol the intros are getting better & better. 😂❤ My brother lives in Australia so when i visit him i would love to meet you in person too 👊

[@PassionforSound]

I'm so glad you're liking the new approach as I develop it further. I don't have a lot of time to meet up with people, but if you happen to get here when there's a show on like the Melbourne HiFi Show then that would definitely work!

[@richardblaauwgeers4349]

I love the new style!

[@PassionforSound]

That's great! Thanks for letting me know

[@WillieBloom]

I started with the TA-22 which I quite enjoy, tube-rolling with various 12AU7 tubes. Then I got the TA-26 because I always wanted the Dark Horse but I didn’t want to buy such an old amp and along came the TA-26. I was a little annoyed that xDuoo released an updated version with the pentaconn connector and yes I know it’s the same amp. I would have liked the convenience without the need to use an adapter cable but I need to use an adapter cable for my 4-pin XLR cables anyway. I’ve skipped over all of xDuoo’s subsequent amplifier iterations… until now. I think I just might sell that TA-26. The TA-22? Dunno. I do enjoy having an amp for 12AU7-rolling. BTW I was able to procure a bunch of Russian tubes (and others) for the TA-26 before the Russian war of aggression. Since the war started Russian tubes have become more scarce and with scarcity comes increased prices. Ah who am I kidding? I’ll buy this one and keep all three for a while. Time will tell what I do with them.

[@PassionforSound]

It can be fun to have different flavours for different headphones. Enjoy!

[@soulfulfool]

about old amps...My tube amp is now probably around 8 years old, bought it when it had 6 years. My point is that good quality old amp can blew out of the water all those shiny made in china newcomers :) (when I think about it tube amps is old tech and people want that old vibe from the past when music was made for pleasure not for analysis)

[@PassionforSound]

@soulfulfool many of the new tube amps are using the same design approaches as older amps. As long as the components are good quality and the tubes too, there's no issue with old or new, but the good thing is that they should all last a very long time

[@soulfulfool]

@@PassionforSound yea we are not loosing the money investing in quality audio gear just because it can last a lifetime (if owner respect and take care of it)

[@chuckmaddison2924]

I'm just listening to a Naim test disc I forgot I had. It's amazing how it sounds. I guess what you feed in makes a big difference to what comes out.

[@PassionforSound]

Absolutely. I sometimes start a comparison test with any old track and think things are similar. I then switch to a high quality recording and that gap often opens significantly.

[@vaneast411]

xDuoo making some great tube gear for cheap I have some pricey HP amps but gravitate to the TA-26 for is forgiving and fun musical presentation right up there with the Bottlehead Crack

[@markothomas9765]

I've always wanted a tube amp. Would you be reviewing the ta22 as well? That is a dac amp combo, if that one isn't that fun, 66 might be the ideal pick up

[@PassionforSound]

I don't currently have any plans to review the TA-22. Sorry

[@markothomas9765]

Thank you Lachlan! Keep up the great work :D

[@pk.002]

I can give my input as I own the TA-22. It's nothing short of phenomenal and easily the best dac/amp I've ever owned, period. I put two Genalex Gold Lion tubes in mine and the presentation is balanced with warmth, rich, and spacious. The stock tubes are good by themselves but I prefer the Gold Lion tubes. I've also tried RCA clear tops which sound more analytical, and Electroharmonix which are the warmest sounding of the sets I've used. It powers my HD 600, and hungrier planars like the Moondrop Para and Moondrop Venus balanced wonderfully. It also drives them great single ended too. My only cons in my use case about the device are as follows: -The menu is a pain to navigate -Class A amplifier generates noticeable heat, so on hot, humid summer days I have to switch back to another solid state amplfier that's more efficient and runs cooler Overall, it has my seal of approval and has my highest recommendation. Apos offers them refurbished which I bought for $415 which makes it an incredible bargain.

[@markothomas9765]

@@pk.002 thank you Peter, this is awesome insight. I will add it to the top of my plan to buy gear list

[@pk.002]

@@markothomas9765 You're welcome! I'm sure you'll love it once you get yours. It's a fantastic piece of kit.

[@Hermann_58]

Hello, will you Report again on the Tube Upgrade for the TA-66?

[@PassionforSound]

If I get time, but that's a little tricky

[@mauriceverstraten844]

Just found my Ta-66 came with the Voskhod from the factory, trying an ubranded 6n2 tube from China atm. Furthermore I got some Philips, RCA an a GE 6080 tubes to play around. It’s a nica little amp for the monny imo

[@PassionforSound]

That's a bonus! Enjoy!

[@maroz73]

Nice review , will that work with a Focal Utopia ? Thanks

[@PassionforSound]

Definitely! It won't maximise the resolution of the Utopias, but they'll be plenty enjoyable 🙂

[@schoi604]

Thank you Lachlan for another great review!! Cheers from Vancouver Canada

[@PassionforSound]

♥️

[@jcisme]

Did you try this as a preamp ? I wonder how this would go into some of the new D class mono blocks like the Fosi V3 mono or some Aiyima offering.

[@PassionforSound]

I didn't, but I have tried the TA-26 and they work great as preamps.

[@Return777]

Currently looking at this amp as a replacement for my Singxer sa-1 jumper modded. Since you have listened to both of them what would you do? I have a Soncoz SGD1 as a dac and Hd800s/ hd 580 black silk. Great vid as usual!

[@PassionforSound]

They're quite different amps, but this will be a great match for the headphones you own, I think

[@Return777]

@@PassionforSound I see thank you for the reply! Which amp would you recommend me in the range of 350-500 euros?

[@PassionforSound]

It really depends on your tastes. The TA-66 is great. I'm not sure what else to recommend that would be better than the SA-1. Is the xDuoo TA-20 Plus in budget in your region? I suspect not

[@Return777]

@@PassionforSound It's in the 500 eur range, I could have a deal on the ta 26-s for 150 eur but yeah

[@PassionforSound]

The TA-26S is great for that price and will suit the headphones you have really well. It might not match the SA-1 in overall performance, but it will be very enjoyable.

[@taho88]

Hey Lachlan, you're saying this should work well with 40 ohms and above. Back in the day I had the Bottle Head Crack paired with a Beyer 770 250 ohm and it was great.I have missed both of them dearly. Now I find myself owning the 770x anniversary. At 48 ohms,do you think they would be a decent match for the TA-66 ?

[@PassionforSound]

That should do very nicely based on what I've experienced here. How sensitive is the 770x? The only concern might be noise if they're as sensitive as something like the DT 700/900 Pro X

[@taho88]

​@@PassionforSoundThanks for the reply. They are 98db.

[@PassionforSound]

I haven't tested the TA-66 with such a sensitive and relatively low impedance design so I don't know if you'll hear noise with them. They'll work well in terms of sound performance. It's just a question of the noise floor of the amp and that can also vary with tubes. It's definitely worth a try if you're able to return the amp if it's no good because the TA-66 sounds great.

[@4ujase]

Tubes like vinyl is making RESURGENCE! I bit the bug and got XDUOO TA-66 tube amp with direct connection wiring, I was really bowled over. Amazing sound quality on a budget. I am currently experimenting on tube rolling. Waiting for adapter/converter 6SL7 to 6N2, hopefully the Psvane Art Collection tube will work. :)

[@PassionforSound]

The TA-66 is pretty amazing, isn't it?

[@4ujase]

@@PassionforSound Have you tried tube rolling the TA-66 with Psvane 6SL7 Art Series using Jemosa 6SL7(6SN7) converter adapter (you can get from AliExpress? Here's my feedback :) I wish I can post you the photos. On the HeadFi forum I had conflictling reports from other people, my first foray into tube rolling, I thought was going to be a costly experiment that went wrong. Thankfully this wasn't so........................phew! Though the Psvane representative alluded to the 6SL7(6SN7) to 6N2 adapter/converter should work in theory because it has the same voltage (6.3v) but slightly higher current. The Royal Mail delivered the adapter today. Excitement and trepidation at the same time, well at least it fits into the 6N2 socket, turned it on, popped on the headphones........Whey Hey ...Rock on Jimmy! I felt like Doctor Frankenstein or Franken-----Steen. Amazing. I can confirm the Jemosa 6LS7 to 6N2 adapter-converter works perfectly and allows you to use Psvane Art Series 6LS7 in the XDUOO TA-66 6N2 socket. I'm getting excellent sound from these tubes. This opens the door for many people who want to tube roll on the TA-66 :) Aesthesics is good too, two large tubes looks better on the eyes, than the generic 6N2 tube, reminds me of a little chipmunk sticking it's head out of golf hole. I've listen to it for only half an hour on my TA-66 and the sound emitting from the Psvane 6SL7 (6SN7) Art Series tube is beautiful. It does require some burning in of course. The Jemosa 6LS7 to 6N2 adapter-converter does what it says on the label. Impressions so far: Silent background More detail Wider sound stage More natural ambience. A little brighter than the generic 6N2 but I think the tube needs to settle and burn in properly. My thoughts: I won't say this has made the sound of the TA-66 double as good but it has improved the sound greatly and for £90 for the cost of Psvane tube, I'd say it's well worth the investment. Final thoughts: Don't waste your time on 12AX7 tube rolling, this is the real deal!

[@4ujase]

@@PassionforSound I think my post was deleted Lachlan I managed to tube roll TA-66 6N2 with the excellent Psvane 6SL7 Art Series. The sound is amazing.I suggest you do a review. You need an adapter converter 6SL7 to 6N2 to make it work 😊👍

[@JošJedan-j2y]

Does it have enough power to drive Hifiman HE6se V2 (Impedance: 50 Ohms Sensitivity: 83.5dB) headphones?​Thanks@@4ujase

[@PassionforSound]

@4ujase thanks for letting me know and sorry about KZbin deleting your post! I've got a whole range of Psvane tubes in for review soon, but not the Art series. Hopefully I can get to the Art series later.

[@JohnMoore-ym1mp]

xDuoo should be able to confirm whether a 12AX7 will work with an adapter. JEMOSA pin adapter is $12 on Amazon. I have a Monoprice hybrid amp in the playroom for my kids, and MP confirmed I could roll in 12AX7's with no problem. Couple years later still no issues. Though I've heard the Voskhods sound great, too. I have a ton of 12AX7s. Now I'm really tempted.

[@PassionforSound]

I had another viewer say they successfully used an adapter and either a 12AT7 or 12AX7 (I forget which) so there's a precedent there.

[@hartyewh1]

Would this in general be the best tube amp for the price? Sound quality being the only consideration.

[@PassionforSound]

So long as you're pairing it with headphones of sufficient impedance, I'd say it's definitely the best I've tried at the price (assuming we're talking pure tube and not hybrid like MT-604)

[@backrack01]

What headphones would u recommend for this? Thinking 2k or less.

[@PassionforSound]

Any ZMF that suits your fancy or either the Sennheiser HD800S or HD660S2.

[@necrodh]

Any AKG

[@RocketLauncherwithInfiniteAmmo]

I like the point to point wiring idea. See if it had been balanced too, that might be asking for the moon on a stick, but I would have had one at the price had it been balanced.

[@PassionforSound]

Balanced OTL tube amps are rare (if not non existent) and generally not necessary. It doesn't improve the sound in any way (assuming both circuits were equally well designed) and it means at least twice as many tubes and the need to buy expensive matches pairs or quads

[@jaybrodnax]

I'd love to know how it compares to Bottlehead Crack (preferably w Speedball)

[@PassionforSound]

Me too, but I don't have a Crack anymore. I suspect the Crack would be comfortably better (and far easier to upgrade with capacitors, etc.)

[@sanchomill]

Hello Lachlan. I'm totally noob in the amp market. I use a Fiio k9 pro and would like to build another combo with a tube amp. My headphones so far : Meze 109, HD6XX, Sundara closed back (EQed as must be). Maybe the Arya Stealth soon. And the HD560S which could be a good combo with a tube amp? I was planning a combo of a fiio k11 (r2r or not combined with a tube amp, in your opinion?) with an xduo, ta-66 or mh-02. I'd really like your opinion to guide me in this unknown territory. Thanks.

[@PassionforSound]

The TA-66 would be great for the majority of those headphones. Depending on your preferences and volume levels, the Arya Stealth and Sundara might not be the best fit, but the rest will be great. You could also consider the xDuoo MT-602 and 604 (604 is brilliant) for a more versatile setup using a hybrid design like the MH-02 but without the DAC.

[@sanchomill]

@@PassionforSound And how do I connect the Fiio K11 R2R dac (RCA and coaxial out) to the MT-604 (XLR in), for instance, please ?

[@PassionforSound]

@sanchomill oh, the K11 is RCA only, isn't it? (I haven't unboxed it yet) If that's the case, you'd need to go with the MT-602.

[@robertrobert2835]

I would ask: TA-66 or Schiit Asgard 3 ? Which of these two will works better as a preamp only connected to active speakers? I have Hifiman EF400 as a Dac.

[@PassionforSound]

I'd probably go with the Asgard 3 simply because tube amps can be noisy sometimes and the active speakers can highlight that

[@aRc11-11]

Why do I have an adverse reaction to XDuoo? Maybe the early clunkers from five, six years past. One reason? Is the egg laid with the hummm- dinger, with the very latest co-op with Drop.

[@PassionforSound]

Is that an xDuoo co-op with Drop? I'm not on there at all these days

[@aRc11-11]

They have "dropped" the ball in that organization.​@@PassionforSound

[@caseyodonnell6621]

Interesting. So tube pre and buffer but solid state amplification (and I'm guessing solid state rectifier)? So it's more of a hybrid than a true OTL, right?

[@PassionforSound]

No, it's 100% tube for the amplification. The rectifier is solid state though.

[@RosemarySoriano-n6v]

Thank you for a great review.😊

[@PassionforSound]

I'm glad you liked it!

[@JTB--]

Xduoo MT-604 is a great little Amp too. Don't pay attention to the price at $170. It's legit. Drives the ZMF Atrium beautifully adding punch/slam. How does theTA-66 sound the more you crank the volume up? This is usually when the cheaper OTL's struggle. More volume = more distortion

[@PassionforSound]

I agree about the MT-604. I love that amp! I'm not one to test amps at high volume because I don't encourage loud listening due to the danger it poses to our hearing. I heard no signs of any issues at "enthusiastic" listening levels though.

[@JTB--]

@@PassionforSound I agree. But I'm a headbanger!! 🤟 I'll probably be be deaf soon because of it

[@shawnrobinson5242]

My MT-604 with Voskhod tubes wiped the floor with my Feliks Euforia. I couldn't believe what I was hearing. Literally, the only thing the Euforia won at was bass extension. That's it.

[@JTB--]

@@shawnrobinson5242 the MT-604 is going for $84 Bucks on Amazon prime today. What a deal/steal. I'm considering getting another one for a secondary HP set-up

[@PassionforSound]

@shawnrobinson5242 the MT-604 is bunches of fun, but I suspect there might have been a bottleneck somewhere preventing the Euforia from performing its best due to DAC, cables, or headphones

[@marcusm5127]

The efficency is typically measured at 1000 Hz meaning that bass and subb-bass requires a lot more power.

[@PassionforSound]

That's not accurate for headphones where there's only a single driver.

[@russellnedland4569]

I love this amp! Ya know what really makes her sing?…………a qutest and a pair of 109s. Lol! But that’s a real testament to how nice this amp is with a good chain.

[@PassionforSound]

That would be a brilliant setup!

[@tek00732882]

Im rocking the TA-20... Xduoo is great.

[@FrantaPo-bc5mu]

Man, this video is visually amazing. Who is clothing you? Great job!

[@PassionforSound]

I'm so glad you liked it! I chose the clothes. Nice to know they look good. 🙂

[@Prxyshj]

Given that the point to point wiring is just simple metal, doesn’t that imply that any investment in high end cables is worthless? In fact it made me think that in general even printed circuit board interconnect is just copper so how can high end cabling at the end of this chain make a difference? And yet there are many people on places like Head Fi who genuinely believe their nice cables do alter the sound. Thoughts?

[@PassionforSound]

It can seem contradictory for sure, but the final wire that runs to the speakers /headphones / earphones has influence too over things like the degree to which very small signal fluctuations are transmitted and the timing coherency of the signal which is important too. The internal wiring of the devices also matter and it's why higher priced gear often (but not always) sounds better - because the quality of internal components and circuit boards/wiring is better.

[@joshuastephens3926]

I still have been unable to find anyone video reviews of the xduoo MH02. If you ever get a chance to test that, I would love some insight into what you think about it as a budget tube dac/amp.

[@hoiley555]

I second this motion. Looks like a perfect combination of what I am looking for but can't find anyone who's given it a solid test or comparison.

[@joshuastephens3926]

@@hoiley555 I have it and it’s really good but I have no other reference and limited headphones to try it with. I would love to see if it’s as good as I think it is or if there is a much higher limit to greatness I have yet to reach. I also don’t know what tubes should or should not sound like. For $150 though, it’s really nice.

[@PassionforSound]

I think I've actually got it coming up for review. I can't access my schedule planner right now, but pretty sure it's in there.

[@shawnrobinson5242]

I tried it for a few weeks next to my MT-604 and the sound was just as good, maybe better, but there is a catch with it. The MH-02 is an RFI...magnet. I tried all kinds of sound eliminating transformers and power strips. I was never able to eliminate enough RFI to make it listenable, but nope. The MT-604 was sitting right next to it while A/Bing and the 604 has almost no RFI issues, so I don't know what was going on with the MH-02. Regardless, I emailed Xduoo and told them the issue. Hopefully, they fix it, because it has tons of potential.

[@joshuastephens3926]

@@shawnrobinson5242 so keep it away from other amps I guess and it will be amazing. I have it connected directly to my iPad on my nightstand and my Meze headphones sound wonderful.

[@michaelorton9887]

Ive always thought the bass was better with tube amps you can here the voice of all the instruments better altjough i like the sound of some of fishers first solid state germanium stuff also ,theirs alot of really good soundingdesigns out their

[@masterazlan6999]

Wow it's looks like Eddie Van Halen guitars..wow point to point...2 wow so far..I'd really like Progressions.. Hmm only things I'd to ask frequently..Does it noisey for an iem?..Peace!

[@PassionforSound]

It won't suit IEMs due to being OTL. It's probably noisy and also will alter the frequency response on most IEMs.

[@progrocker84]

Is the TA66 line-out anywhere close to a Freya+ with stock tubes? Which sounds more "tubey" (as that term is commonly understood)?

[@PassionforSound]

I haven't tried a Freya+. Sorry.

[@clintonwalker5000]

Hi, I’ve got the original Chord TT DAC/headphone amp. I’ve never enjoyed the headphone output on it my headphones are.Adeez lc closed back. I know you have a new TT so my question is what valve headphone amplifier would you recommend which would really be an upgrade from the TT

[@PassionforSound]

I'm not sure how the original TT and TT2 compare, but if you want an amp that's on the same level of transparency and technical performance, but with different sonic character, you need to be in the territory of a Burson Soloist GT or above. What don't you like about the TT output? (Trying to narrow down the field for your)

[@clintonwalker5000]

@@PassionforSound Hi thanks for replying , I look out for Hi-Fi i’m interested in on your channel I think your reviews are great with amazing detail 👍 my original TT sounds thin ,not holographic and there’s not much sound stage. The other thing is I can only listen to my digital streamer through my TT. I recently bought a Linn lp12 turntable which I can only listen to through my headphones output from my amplifier. Which is Luxman 550 AXll pure class A ,phenomenal beautiful amp headphones output is not good ,but still sounds slightly better than TT with my digital ,can’t listen to my turntable with the TT because it’s obviously built into the DAC, So I’m looking for probably Valve amplifier with a holographic good soundstage transparent and very detailed. I’m not looking for much am I 😁 i’ve probably answered my own question but LTA Looks good. is there a cheaper option that can rival the TT/LTA. many thanks .

[@PassionforSound]

@clintonwalker5000 you could maybe look at something like the Auris Euterpe, but I've not compared them directly to know how the LTA Velo stacks up. I would choose the Velo for its tube rolling options and general design and performance.

[@bla_ank]

Do you think the Ta-66 would be a good pairing with 600 ohm Beyers?

[@PassionforSound]

Absolutely!

[@carminedesanto6746]

GM☕️🦘 I’m still rocking the 604🙂

[@TheVeganVicar]

How’s the weather in Toronto today?

[@carminedesanto6746]

It’s actually pretty decent (now that two days of rain ☔️ have gone )

[@JohnClarkW]

I use the 602 and am very happy.

[@brianliu522]

I live in Toronto too, and I love my mt-604

[@carminedesanto6746]

@@brianliu522 Great! Are you going to Audiofest in October

[@moonabhinav]

Dang is it good upgrade over Mt602 or 604? Or should we continue saving for better tube amps?

[@PassionforSound]

It's a decent step up in some areas, but it's also less versatile because the TA-66 needs higher impedance (48 ohm plus) headphones to be optimal. Depending on your headphones, I'd probably recommend saving up for the TA-20 Plus which is more of a direct upgrade from the MT-602/4.

[@rudyvirupakshaiah5818]

I have both, I like the MT604 better, as it's more versatile about about 99% as good...i find the MT604 is better than the TA66 when it comes to dynamics

[@moonabhinav]

@@rudyvirupakshaiah5818 thanks for your thought on them. I do agree 604 seems to be more useful specifically if you have your speakers at an different angle or distance. However I did not find any significant differences between 604 and some other similarly priced chip based amps. I have yet to experience that tube goodness it's seems.

[@russellnedland4569]

Have you had a chance to demo the Drop/Xduoo TA-84? EL84 power tubes for way more accessible rolling options.

[@russellnedland4569]

$399 (US) w/ stock Psvane classic tubes!

[@PassionforSound]

I haven't tried that one.

[@soulfulfool]

True test for tube amps are 600 ohm headphones or from my personal experience ADX5000 420 ohm :) they are a tool to check any amp especially tubes, best balanced sound of all imo (ZMF headphones also since they require much clean power to be fast and punchy). I left comment for Zach that Im really passionate about 600 ohm headphones and it would be brilliant if he could make special edition 600 ohm ZMF's, he seems to like that idea as new challenge 🙏😉. I promised him that I will be first to order Atrium 600 🤣 word given I hope it came true and start to save small fortune for it

[@ishaajo2715]

Will it be able to run properly Very High impedance headphone like Beyerdynamic T1 v1 600 Ohms?

[@PassionforSound]

Absolutely! It's made for that 🙂

[@Rezzzn0r]

Hmm maybe I should try it... I've never owned tube amp. Is it compatible with IEM?

[@PassionforSound]

Not really. You're better off going hybrid or transformer coupled for IEMs at this price level. The OTL designs will alter the frequency response of most headphones due to having higher output impedance. They're also likely going to be noisy with IEMs because they're designed more for high impedance headphones.

[@Rezzzn0r]

@@PassionforSound awesome, thanks bro. I will stick with my Mojo2 then ;)

[@marekkordzik7517]

I think Im good with Feliks audio echo mk 2 ....

[@PassionforSound]

Definitely 🙂

[@Prxyshj]

What do you recommend for ZMF Caldera Closed? Also are there portables that can power TOTL headphones?

[@PassionforSound]

If you've got the budget, I'd look at a higher level tube amp from Feliks or Linear Tube Audio for the Caldera Closed. There are plenty of portables that will drive those too, starting with the Chord Mojo 2 as a great option.

[@Prxyshj]

@@PassionforSound this may sound silly, but I just don’t like the way the chord looks. It’s a bit … plastic looking. I like the xduoo looks but they might be a bit big for true portability. I assume a Qudelix 5K is underpowered for it

[@PassionforSound]

I'm not sure about the Qudelix, but it's quite possible it would be fine. Being battery powered means it should have decent power output (as opposed to USB only powered dongles). If you're after a better cable option for the ZMFs (which do look and feel a bit plastic), the Apos Flow cables are a great option with ZMFs (if you're in the US, Canada or Australia)

[@jeffhernandez5098]

Are OTL amps good for lower impedance headphones? Say 32 - 80 ohm.

[@PassionforSound]

You need to be a bit selective as it will depend on the specific output impedance of the amp. This one is good for headphones from about 50 ohms and up IIRC. I'm pretty sure I covered the specifics more accurately at the end of this video.

[@russellnedland4569]

Will the Meze 109 pro tolerate the high impedance of this amplifier?

[@PassionforSound]

At 40 ohms it should be ok. The tonality might shift a little, but I wouldn't expect much shift.

[@russellnedland4569]

@@PassionforSound What headphone would you recommend for stepping into high ohm otl tube use around, say $500 or so?

[@russellnedland4569]

I did a bit more homework and realized hd6xx is a good inexpensive starting point. I love your reviews and the fact that you answer fan questions, patron or not most don’t.

[@PassionforSound]

@russellnedland4569 any of the Sennheisers from HD600/6xx/650 and up or the Sivga SV023 would be my choices.

[@PassionforSound]

@russellnedland4569 great choice. Always happy to chat to viewers! 🙂🙂

[@jw-lk1pe]

So I think you can actually use a 12ax7 tube...all you need is an adapter that's easily found on ebay. I am thinking of buying this amp, but the lack of tube options threw me off. Has anyone successfully used a 12ax7 with the adapter? If it's good, It might be game on for me

[@PassionforSound]

That's correct - either 12AX7 or 12AT7 (I forget which, but I believe it is the 12AX7) will work fine with an adapter. I've had others mention this and I've ordered an adapter to try for myself...

[@boyanddog]

What are the advantages/disadvantages of an OTL amp having two input stage tubes and two output stage tubes over one and one?

[@PassionforSound]

It will largely come down to the specific tubes and circuit design, but more tubes can provide more power (although not a guarantee), can lower output impedance (also not a guarantee), and means you almost definitely have to buy matched pairs of tubes. 🙂

[@randolphlee3025]

Mr. Lachlan, I have a pair of Grado GH 3, I would like to find a robust amp to drive them I think they are 32 OHM

[@PassionforSound]

OTL amps won't be your best bet. What is your budget?

[@ixoye56]

I would probably love the design when I was 17, but now at 67 not so much 😄

[@jaybrodnax]

I love Xduoo products, especially their visual design. I HATE blue LEDs though

[@PassionforSound]

Yeah, blue isn't my favourite either. It's nice that it's diffused behind the volume knob on the TA-66 though so it's not piercing and uncomfortable like a direct view to a blue LED

[@tshM-ie7qd]

What a nice talk.

[@HACTube77]

For HD650 which one is better TA-66 or Mojo 2? Thanks before

[@PassionforSound]

That's a very personal preference decision. The Mojo 2 will deliver more resolution and a more neutral sound. The TA-66 will be more coloured and a touch richer with lower overall resolution.

[@kenaiello4851]

Run this into my reisong A10 might be good

[@TheMaurob1979]

I wonder if can drive also the hifiman 400 se

[@PassionforSound]

That might be a stretch because the HE400 SE is quite hard to drive.

[@jefffeith4201]

I wish xDuoo made amps to drive speakers too.

[@PassionforSound]

That would be brilliant!

[@palefaced1]

Totally different price point, but the ZMF OTL is the best OTL amp I have ever heard.

[@PassionforSound]

I'd love to try it

[@johnratcliffe6438]

How are you getting on with the Aero DAC?

[@PassionforSound]

Loving it and excited for the review!

[@Mixail747]

Can it be used with IEMs? Prolly not coz of sensitivity?...

[@PassionforSound]

Yep, sensitivity and lower impedance of IEMs will mean that most aren't a good match for an amp like this one.

[@afico6172]

Did you test with som can 600 ohm like dt880? Should be able to drive them ?

[@PassionforSound]

Yes, it will drive the 600 ohm Beyers beautifully too

[@afico6172]

@@PassionforSound i asked this because my previous ta-26s went into distortion with them and the sound was too open

[@PassionforSound]

If the TA-26 couldn't manage them for you, the TA-66 won't either, but I suspect the problem isn't just the amp as it should have PLENTY of power. I'm guessing you're either listening very loud (please don't hurt your ears) or using EQ. Are either of those the case?

[@paulyllow]

How is this compare with Schoit Vali 3 or Lyr?

[@PassionforSound]

It's quite different from the Lyr because this is OTL and Lyr is hybrid. I haven't tried the Vali so can't comment there - sorry.

[@kenaiello4851]

Hows the preamp?

[@PassionforSound]

It's great. It uses the same basic circuitry as the headphone stage so you can translate all of the same qualities to the preamp performance.

[@kenaiello4851]

@@PassionforSound Thank you 😊

[@michaelorton9887]

I hope they keep it at a low price for quite a while so i can save up to buy it

[@PassionforSound]

I've never seen them raise prices of existing products before so you should be fine.

[@Mark-rw3kw]

More direct wiring paths? The electrical circuit design of point-to-point wiring is not different than using a circuit board, unless they are two different amplifier designs. There "may" be other advantages, but often in a simple circuit like this is often less complicated to use point to point wiring, just like is used in many simple speaker crossovers.

[@jaybrodnax]

Does the size of the "wire" matter? If find it kind of amazing how small tiny traces work, especially when people talk up the benefits of better power cables and headphone cables

[@Mark-rw3kw]

@@jaybrodnax Yes, that is a contradiction. But large cables generate a lot of revenue and a talking about them generates a lot KZbin views and ad revenue. I noticed in this amp, the point-to-point wiring doesn't appear to be copper (and not likely silver), and it is not shielded. Looking at the inside of the amp, it looks like the point-to-point wiring is probably the easiest and cheapest solution for such a simple tube design.

[@PassionforSound]

Traces in circuit boards are also not shielded. The wires in the TA-66 appear to be silver-plated copper. Also, by going point-to-point, each wire can take the most direct possible route to the next component. This reduces the length of the pathways which will improve the circuit by reducing the filtering effects that ALL wiring/traces have on the signal. Less wire/trace equals less filtering equals more transparent circuit.

[@Mark-rw3kw]

@@PassionforSound I maintain that you could not hear the difference (in a blind test) if this amp had a well designed printed circuit board (PCB) vs point to point wiring. Properly designed using copper, a PCB can perform just as well as a point-to-point wiring in an amp. But for a tube design this simple it doesn't need a PCB, and using one would make it harder or more costly to build and harder to do revisions. Also, it appears that a lot of so-called point to point wiring in this amp is going to the output and inputs, which would usually be point to point even if using a PCB.

[@PassionforSound]

@Mark-rw3kw I don't really understand the point of this and what you're trying to prove. There's not a debate to be had here.

[@necrodh]

Xduoo is a legit audio brand they dont need to lie like others

[@brucetaylor7095]

What is the required voltage for this amp?

[@PassionforSound]

What do you mean, Bruce? If you're talking input voltages, I think it has a voltage selector switch for 110/240V.

[@brucetaylor7095]

@@PassionforSound Great thanks, I couldn't find the input voltage anywhere.

[@progrocker84]

I recall seeing on a forum that the amp hums until the front tube has been properly burned in. I can confirm that tube burn-in removes the hum through headphones. However, I'm still hearing the hum through my speakers even after 50+ hrs of burn in. The hum is only present when no music is playing. Does anyone else have this issue? Great headphone amp otherwise.

[@0rogontorogon]

Thats correct, tubes require some "burn-in" before they reach peak performance. My guess is that your speakers have a far lower impedance than your headphones do. In my experience preamp tubes are a bit of a lottery regarding hum and/or microphonics. If one hums after completing break in time it will likely hum for the rest of its life. If it annoys you, replace the tube and hope for the best.

[@PassionforSound]

Great advice above.

[@jw-lk1pe]

does the 26 have a dac?

[@PassionforSound]

No. Both of these are pure amp and pre-amp only.

[@0rogontorogon]

Sadly tube rolling has reached a pricepoint that makes no sense anymore for $250 6as7g/6080 amps. These tubes are in dire need for new production versions, but sadly nobody makes those. I suspect the factory equipment is not available anymore (afaik new production pentodes are made with the original factory equipment relocated to the new factory, like Gold Lion tubes).

[@PassionforSound]

That's exactly the case. I think there might be one or two factories making 6AS7G/6080 tubes, but it's becoming more difficult to track down good and affordable options. I suspect we'll see a shift to alternative power tubes for future OTL amp designs.

[@Atomicman123]

Nice Review! Even your given compatibility specs do not fit, do you think it will run a DCA E3?

[@PassionforSound]

The E3 is probably a tough call for it, but it might scrape through.

[@joshchacko7729]

Thanks man.

[@PassionforSound]

My pleasure 🙂

[@danisold]

There is a 6sn7 to 6n2 converter on Amazon, i searched 6n2 tube converter. Would that work in the ta66. Anyone have any experience with that?

[@PassionforSound]

I haven't looked into that. Just be sure that the electrical requirements align before plugging it in. Adapting pin layouts doesn't mean the voltage and current requirements will match. 🙂

[@danisold]

@@PassionforSound I was underwhelmed by the ta-66 paired with the hd6xx headphones. I have a schiit vali 2+, a wiim mini, an su1 sml dac with akg 371 headphones that sounds so much better. I also have the saga plus in a speaker system where I tube rolled the stock 6sn7 tube. I used a psvane se... forgot the exact one and the ray 6sn7 select. The ray paired with the preamp and my pioneer sa5200 sounded too bright, so I went with the psvane. I was about to send the ta 66 and ray select back, but I did buy that jemosa converter off of Amazon. Figured I'd give it a shot--as far as I could tell, it was a proper converter, but who knows. Long story short, this sounds so much better with the ray tube in the 6n2 spot. Definitely considering keeping this Frankenstein system, lol. Also have the 12ax7 to 6n2 converter. May test some other tubes.

[@PassionforSound]

Thanks for sharing!

[@SuperSeltzer]

The secret to TA-66 excellence is in hardwiring design! I love Darkvoice for the same reason. If you like DV you will love TA-66 also. The only gripe is that the transformer hum is more audible than in DV which is very silent.

[@PassionforSound]

I have zero transformer hum in the TA-66 I received

[@markmorrison3090]

@@PassionforSound The noise is strange since it doesn't always occur. It seems to happen randomly.

[@PassionforSound]

I wonder if it's picking up noise from your phone or some other device nearby?

[@SuperSeltzer]

@@PassionforSound My Darkvoice next to it is silent. Maybe it is better behaved under 220V , I don't know. I live in the US. Anyhow it's not that loud, only barely audible when music isn't playing.

[@PassionforSound]

@SuperSeltzer hmmmm. That's curious and makes me wonder if you've got a faulty tube of a faulty amp. Have you tested different tubes?

[@ThinkingBetter]

Better not buy some US$5,000 RCA cables for this one hahahaha