I blind-tested, to the best of my ability, my Enleum AMP-23R against an Atom amp (made of plastic!) with Hifiman’s Susvara and couldn’t tell a difference. I have mild hearing damage but it shouldn’t be that bad.

Besides the Susvara, I also tried Focal’s Clear and Audeze’s LCD-5. The Clear isn’t said to “scale” particularly well and I’m not familiar enough with LCD-5 to have heard differences there. This was done in my quietest room, which is acoustically treated and quite silent.

That said, I am not a practiced listener by any means and my audio pursuits are based on feelings of “this sounds like live”. I did this test alongside an upgrade-chaser with more discerning ears and we came to the conclusion that it didn’t make an audio difference but they look or feel nice. Our findings weren’t upsetting, I primarily upgrade for aesthetics and wasn’t aware that it was meant to sound better.