You miss nothing if you get something like a Rowland Concentra II, Pass or any of the great solid state amps out there. I have heard more glare from some KT88 equipped amps than I have ever heard from my Rowland with bad CD material. The biggest factor however is matching the amp to the speakers...tube or solid state.
From tubes to solid state. What do you loose...
...if your priories are transparency, timbral acuracy, micro dynamics and soundstage? I am hesitant to give-up on my Sonic Frontiers Power 2, but buying tubes every so often can be quite expensive. The current tubes offered (Sovtek, Svetlana, EH) are short-lived and not cheap either. I will probably stay with tube pre-amp and go with the ss amps, like Mark Levinson...?