We talk a great deal about the sound of an amplifier: warm, big, thin, weak, transparent, musical.
Truth is, what we're hoping for is no sound at all.
Not the sound of sterility, mind you, but the "sound" of nothing. As my good friend Peter Moncrief used to write about in his magazine, IAR, the sound of a straight wire with gain.
Amps shouldn't sound like anything.
Just amplify exactly what's there without affect.