It's an old review from 2019. Since then, Amir's methodology has improved and new tests have been added.
Here are back-to-back measurements of the LA90 and AHB2 to compare to each other:
https://www.l7audiolab.com/f/topping-la90/
https://www.l7audiolab.com/f/benchmark-ahb2/
4Ω:
View attachment 304625 View attachment 304623
8Ω:
View attachment 304624 View attachment 304622
Nice. It's also nice to see that the lowest distortion is at 10W, where the louder transients would be when [properly] listening to the amplifier near its loudest. Although I'm sure at this level of performance it'd be impossible to tell if 10W had the same percentage distortion as 1W, it's still nice knowing that the louder parts -the ones most easily heard- are also the clearest!
Sometimes it's good how revealing audio equipment is, but lately especially, I've been finding that sometimes, it's not...
My best speakers (acquired a few years ago--
"vanishingly low levels of distortion"), I've finally driven them with a VERY capable source: my Topping G5 headphone amplifier/DAC combo (very new). I settled on it after looking for a portable-ish combination DAC and headphone amp - something that could drive both my high and low impedance cans and possibly even drive my speakers directly for lower-level extremely high-fidelity. The G5 was everything - the review here showed power output/voltage and distortion all the way down to 12 ohms, (...24, 20, 16, 12 ohms) which illustrated a clear trend with no reason to think the good news was going to change (especially since, as expected, peak voltage just dropped a bit with each decrease in impedance. With this and the extremely low output impedance for a headphone amplifier of just 0.1 ohms, I hooked things up with great expectations
My o-scope, monitoring the G5's output as it drove the speakers, showed 10-13V peak to peak / 1-1.3VRMS with the ZZ Top Eliminator album. No clipping, just nice waves. Very powerful for a headphone amp!
Aside: Earlier in life, I thought Eliminator was recorded pretty well - better than average for 1983. Not an audiophile recording, but a recording done right-obviously in a studio with good equipment. No distortion, levels of everything were always good, they didn't use any bad equipment like microphones with horrible high frequency response, the drums were good, and tape hiss? Only audible during the last bit of the fade out of a song or really quiet parts.
Well was I wrong about Eliminator! Not all of it, generally they did a good job. Just somehow, the entire album is distorted! It's hard to describe because the distortion is not typical clipping you migh expect it to be, being on everything. It's the entire signal apart from maybe the vocals, I can't say for sure but the vocals sound pretty clean. Anyway, the best way I can put it is low level electric guitar distortion is on
everything ... This was not obvious even with an Audigy 2 and Audigy 2 ZS notebook + AKG K240s, or any of my mid-fi systems I had in life up 'til now, cars, friends mid-fi systems up 'til now...
With really REALLY good and low distortion equipment, things are going to be revealed to you in the music you love, and you might not be able to enjoy it as much afterwards, because once you've heard a problem, you know what it is and what to listen for, and from that point on it becomes really obvious even through other systems. Not to other people - if they didn't hear what you heard through your system the first time they won't pick up on it even if you describe it.
Maybe it's a bigger deal to me compared to others because in addition to loving music, sound reproduction is almost as important to me