I understand what you are saying but I am insistant that their is coloration of sound (defined as deviation from 100 true reproduction ) that is not snake oil. I agree that theoretically all amps SHOULD sound equal but in practice they do not. Whether this is from the manufacturing process introducing things such as harmonics, poor attenuation of signal, electromagnetic interference from poorly shielded electronics - I know not but the difference is there and notable.
I don't believe in the diffeences in speaker wire (BTW I use 14g lamp cord of a spool from Home depot at like 11 cents a foot or so ) and different brands of HDMI cables all sound the same - snake oil and pseudoscience are things I definitely don't believe in but evewn weel respected audiophile journals / websites will acknowledge that there is a difference in the sound of amplifiers and they will also solidly refute the things such as wiring (provided sufficient gauge for the length of run is followed).
takes a lot of things based on opinion or faith and represents them as fact which I certainly don't.
Example - when I bought my projector screen I was sorried that with my speakers behind it that not buying a perforated screen designed to be acoustically transparent would make a difference but repeated blind test (actually wearing a bnlindfold) and listening with the screen lowered vs. raised I both my wife and myself can not notice a difference at all.
Edit : Bislander -here is a part of an article that looks/describes scientific and objective measurements and reasons why amps may sound different
actually what I had posted was too many characters to allow the post so here is a link to the article
These are the variables addressed
Total Harmonic Distortion (THD)
Transient Intermodulation Distortion (TIM)
Open Loop Gain
Open Loop Distortion
Open Loop Output Impedance