High-end amplifiers no matter what type or the class are , have a level of sound quality that no difference in sound can be heard in blind test.
Regardless of whether it is tube amplifier or solid state class AB, or class D, blind test show that listeners can not recognize which amplifier the sound is coming from.
There are blind tests and double-blind tests. Blind test means that listener does not know which amplifier is playing, while operator who switches amplifiers knows which amplifier is playing.
Double blind test means that neither the operator nor the listener knows which amplifier is playing.
One of the best articles about double blind tests of high quality amplifiers you can read here: