I never thought that the source material and music I listened to would matter much with SS or Tubes. I have heard both and prefer my SS amps. I run Yamaha M-45 amps and I like them. They are MOS-FET amps with a unique biasing circuit that runs AB up to 5 watts and Class A above 5 watts. Prevents the crossover distortion push pull SS amps are plaqued with.
For the record I think the warm sound of tubes comes from two places.
1. Overdriving the amps because they don't have enough power and we want more sound.
2. Different dampening charactoristics - tubes offer good speaker control, better than many SS amps.
One downside to tubes for sure is the danger of a broken speaker wire. An open circuit to the speaker may cause damage to the tube amp.
The MOS-FET offers tube like charactoristics, but of course there are now electronic signal processors that claim to do the same thing. Winamp has a plug in that simulates valve sound even.