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 BOXBone 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 A20If 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 A5One 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 UPSHOTI 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
