The hyperbole isn't "scientific" and defocuses people from the important elements of what you said. I'll try to pull out the signal from the noise
Yes, I assume people do level matching, it has been my experience over a very long time - 5 decades - that people are smart enough to figure that out on their own, and it is rare to the extreme I've met someone that is working against themselves by not doing that. A couple of quick examples sets them straight, and that is all it really takes to move forward.
If that is all you had/have to offer, you could have simply replied to his posted results asking if his testing meets those criteria. I've never needed to say that myself, as I said I've rarely run across someone that didn't know that very early on in their appreciation for audio.
And, your comments about tube equipment really doesn't wash with what those that actually enjoy tube equipment experience daily.
We aren't trying to beat the measurements of SS tuned for graphs, we are tuning our hardware for listening pleasure.
The Topping A90 is a good example. I enjoy it immensely, but it doesn't satisfy me like a good tube amp like the TA-20, or another SS amp like the FiiO M15. Yet the A90 measures near the top of SS amps here on ASR.
@DeepSpace57 hit upon the next stage in my search for improving the TA-20 sound, replacing the OPAMP for better fidelity - measurements - and changing the Capacitance for better power availability, perhaps better Bass. Component changes to tune for using the E80CC or 12BH7 tubes.
Then we can feed our findings back to Xduoo - they probably already know all of this and simply optimized performance vs costs - and perhaps we can get a better TA-20 generation out of this work?
Or at least a couple reasonably affordable kits of optimizations to share with other TA-20 owners.