I need to voice my opinion, although I'm biased....
Yes, there is a lot of snake oil in the Audio Business, I'm not going to pay more for my speaker cables than my speakers, 2.5mm2 stranded wires are fine. And those that believe in "audio grade" fuses, I would like to sell the eiffel tower...
But there are also things that's hard to measure, simply because there are complex things going on and audio measurements methodes aren't really that advanced, mostly using static signals. The Human ear is an amazing thing, able to hear tiny details.
And negative feedback are not a good thing, but a solution to fix not that linear and usually bandwidth limited designs. Read up on Nelson Pass's Article at
https://www.passdiy.com/project/articles/audio-distortion-and-feedback, there are also other good articles there. Anybody rememeber Matti Otala and his work ?
It is possible to design amplifier circuit with low distortion without using negative feedback, just not that easy.... My dac1541 typically get 0.003% THD at full signal level without negative feedback, it just takes 50 transistors per channel, most of them to ensure that the amplifying parts operate optimally....
And btw, if I had the choice between any old Ferrari and a new fancy Japanse sportscar, I'll take the Ferrari without a second of hesitation....