As a designer of both tube and ss amplifiers, I am somewhat surprised that the main reason for the preference of tube amplifiers by some seems to have gone adrift. That is the sometimes inherent nature of ss amplifiers to generate listener fatigue because of poor distortion performance. Not to go too technical here (it is not the subject, as well as that it has been extensively dealt with elsewhere): One all too often is presented with the weary old spec of 0,001% thd, saying nothing about the nature (spectral content) of the distortion products, thus in reality saying just about nothing at all.
I am not too conversant with many commercial products, but have too often seen poor high order harmonic performance, which is one of the single greatest problems with many ss amplifiers. That to my mind is the reason for a host of favourable phrases used to describe tube amplifier performance in comparisons. (Tube amplifiers, even middle-of-the-road-designs, do not easily develop high order harmonic distortion.) Apart from aesthetic/cult reasons, people seem to put up with the greater cost and bother in upkeep of tube designs because of the lack of listener fatigue phenomenon.
Having said that, it is rather problematic to quote preference of tube amplifier A to ss amplifier B or vice versa, in support of general preference of either type. There are good and poor examples of both modes, and the customer who has to make a decision based on (subjective) comment alone has my sympathy. A thorough analysis only of amplifiers, as is sometimes seen in e.g. Stereophile, might reveal purchase preference. Listening is fine, but I am sceptical of the chances of being able to judge well only from a limited period of listening in a dealer's "auditorium".
