[Jon L]

Some of the Aiyima A20 reviews have called it the best-sounding Aiyima amp to date, which is not surprising since it's Aiyima's 10th Anniversary product and their latest release. 

But then again, some have called Douk A5 amp the best sounding TPA3255 amp to date, though Aiyima A20 was released after Douk.  A lot of ink has been spilt by me regarding Douk A5, so yeah, it's game on.

https://www.audiocircle.com/index.php?topic=191882.0



Funny enough, the price difference between the two is pretty much reflected in the size difference, but does Aiyima sound twice as good?

OUT OF THE BOX

Bone stock, the Aiyima does sound a bit better to my ears, a smidge smoother with finer textures.  Still, neither will make it into one of my permanent systems without some additional help.   

More specifically, the main thing that elevates these amps from "good for class D" to "does music justice" seems to be a better power supply.  The stock 48V/5A GaN smps power supply is the same for Aiyima and Douk and does a good job really, but the last 5-10% that keeps you involved and engaged in music is not quite there. 

Both amps benefit significantly from being powered by 36V Lithium battery, which reveals more detail and clarity while paradoxically making the sound warmer and more forgiving.  There is just more musically relevant vividness to timbre and tone that pushes the amps across the threshold of daily usability. 




CASE FOR AIYIMA A20

If someone switched amps while I wasn't looking and casually listening, I don't think I would be able to tell that happened.  Instant A-B switching of amps is difficult, so who knows, but the underlying TPA3255 sound signature is amply present in both amps, i.e. clean, detailed, neutral sound with good bass without bloat and linear midrange without overt warmth.  Battery adds some delicacy, clarity, timbral authenticity, and involvement, and I could live with either amp happily in one of my systems. 

However, there are reasons to use Aiyima over Douk.  One reason is the fully balanced design of Aiyima, as Douk is single-ended only.  Not that single-ended inherently sounds worse, but in the case of Aiyima A20, and also Aiyima T20 tube preamp, their circuitry derives single-ended signal by using additional opamps to convert balanced signal, so by using balanced connection, signal path becomes purer. 

Another reason may seem like an odd one, but it's the "Bypass" button present on A20.  It's not clear to me what exactly is bypassed, but in non-bypass mode even with the volume knob at max, the sound is significantly different from bypass mode.  I wonder if this is the effect of the physical volume pot just in signal path or something else is involved, but the difference is at least as large as changing cables or opamps IME.  This is a plus in my mind because one essentially gets two different amps in one.  I can press the bypass button (3 sec) while music is playing without any ticks or pops, enabling instant A-B comparisons.  Bypass mode does give you more detail, especially in treble and upper midrange, but this is a double-edged sword when it comes to poorly-recorded music from early days, which sound "better" in non-bypass mode.  As expected, shaving off a bit of treble energy results in midrange sounding richer and more forgiving.  I wish Douk had this bypass button. 

In addition, Aiyima comes stock with nicer replaceable opamps (LME49720), and one need not replace them to get good sound out of box.  The fact it also has seven (!) non-replaceable opamps (NE5532) is both a blessing (money-wise) and curse (inflexibility). 


CASE FOR DOUK A5

One obvious plus is the lower price, essentially half of Aiyima for same power output.  Size being half is also an advantage for people using it on desktops or tight spaces.

Another plus is the glass lid on top for easy opamp rolling.  I really wish Aiyima had this feature because it is a pain opening the case to roll opamps, and the tight space inside Aiyima does not allow many of my expensive discrete opamps.  For Douk, I can install huge opamps without opening the case by leaving the glass lid off.  This is quite necessary because Douk A5 does not sound excellent with stock NE5532 amps in sockets (with stock power supply).

A fantastic feature on both amps is the high-pass filter function with subwoofer line-level out, which allows one to roll off bass from main speakers and hand bass off to external subwoofers, cudos to both companies.  However, one obscure feature of Douk is that while its subwoofer output is regrettably a 3.5mm TRS jack, it does output both left and right signals enabling one to use stereo subwoofers for those so inclined.  Aiyima's sub output is a typical mono RCA jack only. 
 

THE UPSHOT

I am done buying any more TPA3255 amps since I have two Douk A5's and an Aiyima A20.  With some power supply and opamp TLC, either one is capable of sounding mighty musical and satisfying at ridiculously low prices, even more so before tariffs.  I say this while looking at a bevy of other traditional amps in my room including 300B SET, 2A3 SET, 45 SET (previous), 829B SE, EL84 SEP, as well as bunch of traditional solid state amps and other class D, even GaN, amps.  They all have their place, but heck, combined price of Aiyima and two Douk's only buys half of my Takatsuki 300B tube 

[NIGHTFALL1970]

Jon L,
With my A5 I found that the 48V/10A power supply makes a huge improvement in sound quality.

[Jon L]

Jon L,
With my A5 I found that the 48V/10A power supply makes a huge improvement in sound quality.

Unfortunately, 48V/10A supplies cost almost as much as a Douk A5, and I truly doubt the character of sound improvement will be in same direction as battery power.  Heck, I should sell the three 48V/5A power supplies..

[Jon L]

What we have here is the ludicrous situation of pairing a $170 amp with $12,000/m Audioquest Dragon XLR Cables


Just kidding, they're clones 

[Jon L]

Ordered a second A20 on Black Friday sale.  The more I use the A20 with different cables and gear, it's more obvious to me it's a dang legit amp at a crazy price.

Now I have two of each:  Aiyima A20, Douk A5, FU19/FM30 tube amps!

[Jon L]

SPARKOS SS2590 PRO



I installed Sparkos SS2590 Pro opamps in Aiyima A20 using various trickery including bridges, flexible extenders, and using the chassis as bottom heat sink.  What a pain but it sounds like I added a couple of bass woofers to the system 

After more rounds of laborious opamp rolling, my conclusion is that if one does not already have Sparkos SS2590 Pro in the system, using them in Aiyima A20 will simply transform the system to the next level, especially in terms of Niagara Falls level of dynamics, flow, and naturalness.  It's like you are upgrading your garden hose to twice the diameter for music to explode through. 

One caveat is that if you are already using Sparkos SS2590 Pro upstream with abundant naturalness, and if your system has other elements that already smooth out upper-midrange/low-treble area (in my case, "Dragon" interconnects, Alnico drivers, and battery power supply), adding more SS2590 *may* sound a bit overly smooth and rich with certain smooth recordings. 

[Jon L]

BURSON V7 VIVID



V7 Vivids synergize better here than in my DAC's output stage, where it can sound a bit well, too "vivid."  Coming in after upstream Sparkos SS2590 hands off plenty of naturalness, dynamics, and bass power, the combined balance is extremely satisfying and well-balanced. Plenty of detail with black ground is appreciated, as well as the absence of subtle, almost subliminal textural grain monolithic opamps like NE5532 tend to bring to the party.  This combination of Sparkos SS2590 and Burson V7 Vivid is highly recommended.

BURSON V7 CLASSIC



Another excellent combination with Sparkos SS2590 upstream, just slightly less vivid compared with V7 Vivid with a bit richer, thicker presentation extending into bass region, which has more quantity.  Like tube rolling, there really isn't one "best" choice because the system balance will change by what tube comes before or after the tube being rolled.  It's really a tossup between Vivid and Classic, but Classic does inch more towards the sheer bass power and weight of Sparkos SS2590. 

OPA828





OPA828 is an audiophile favorite, and when it doesn't have to create extra richness and dynamics by itself as in this combination, it really does a faultless job.  It is probably one of the very few monolithic opamps that seem to avoid the subtle textural grain.  In this position, textures are buttery refined, and sonic spectrum is well balanced and detailed.  It really does sound more modern with more resolution compared to opamps like NE5532, LME49720, and even the venerable OPA627.  If one wanted to avoid paying for discrete opamps but wanted a change from LME49720, this is the one.  LME49720 does sound a tad more lit-up in upper-midrange but less buttery smooth, so depending on which direction your system already leans, a different choice may be favored. 

 

[Rocket]

Hello Jon,

Thank you for the detailed review of your chip amp adventure.

Cheers Rod

[wushuliu]

The Virtual Hifi Supersonic/Hypersonic opamps might be worth trying out as well, assuming the amp board provides enough power. The opamps are basically stacked 5532s IIRC, which I've heard good things about over the years for diy but no one's ever offered commercial versions before that I know of.

[Jon L]

The Virtual Hifi Supersonic/Hypersonic opamps might be worth trying out as well, assuming the amp board provides enough power. The opamps are basically stacked 5532s IIRC, which I've heard good things about over the years for diy but no one's ever offered commercial versions before that I know of.

I haven't seen definitive list of which opamps Virtual Hifi is using inside, but I have decent idea at least some use opa1656 and some likely uses NE5532 (maybe Supersonic V2? which is described as using "bipolar" opamps).

I currently have stacked LME49720 running inside Aiyima A20, which is not THE top opamp but works great as second opamp after getting signal from the source's Sparkos SS2590 Pro.  If I use SS2590 in both source and amp, its "flavor" getting doubled may be too much of a good thing for certain systems.  Same goes for many/all(?) opamps IME. 

If I ever get the motivation to buy and parallel some opa1656, that would be interesting but I am opamp'd out..

I wrote about stacking opamps here on Audiocircle:
https://www.audiocircle.com/index.php?topic=192996.msg2023215#msg2023215