Proposing a "tweak" is not the same as designing an amplifier..
For example i had a better experiment to propose about for sure what cannot be measured BUT could be heard :
Put a 250 gram of quartz on your amplifier...
Put a 250 gram of shungite on your amplifier...
Put the two together now...
You will hear a difference...
I fine tune my S. S. amplifier with these minerals tweaks... Really for the best...
But tweaking is not designing... No more than walking with better crutches are like installing an up to date prosthetic legs or growing a new one ..
And an improvement by design is always better than tweaking a design... So good the tweaks will be ... And they will if you know what you do with your ears...😊
But all of what we can learn from a component and hearing if we learn how to modify or tweaks it are not all measurable...If we tweak...
But if we design , all that we made MUST BE measurable, by defintion of a good design... And it is better if the designer as atamasphere know about harmonics for sure... And i will trust him precisely because of that...
And he knows that objectivist as subjectivist are deluded focussing on the gear but forgetting about psycho-acoustic basic ...