There are many who believe in just that.
Have a read through this http://www.head-fi.org/t/486598/testing-audiophile-claims-and-myths
Mind you if you think you can hear differences, so if you think so. I don't want to argue with you about it as it is your enjoyment of your equipment that matters.
There's data available though that prove measurably different frequency responses and dynamic range characteristics between different amps, so I'm not going to agree that black is indeed white for the sake of political correctness and/or not offending anybody :-P (No offence meant, of course)
Bringing it back on topic; for certain music, I'll listen to my 400s through the valve amp, just to tame down that treble spike. To be honest, there isn't a night and day difference between the sound from the Bravo Audio Ocean to my Asus STX. The Asus has more dynamic range and extremes of frequencies, but the Bravo has more warmth and smoothness (to be expected from a valve) and seems to (getting subjective now) gel the elements of music together more cohesively, or more naturally, possibly at the expense of pin point imaging. Anyway, most of the time, the latter effect works well for my tastes with the HE400s.
I'm also trying to make the point that, despite the obvious differences on paper of the above mentioned amps, their respective 'sounds' are not worlds apart. There are subtle differences, yes, but it's not make or break.
Happy listening, people. Listen to what YOU want, how YOU want and (if you're lucky) when YOU want!! :-)
Edited by amigomatt - 11/15/13 at 3:22am