I am a tube person, but, more specifically, I like low-powered triode tubes (I run a SET 2a3 amp in my system). There is nothing quite like a SET amp to get all the beautiful harmonics and texture of instruments right and to get notes to bloom naturally into space and decay naturally. To me, a lot of amps get the attack of the notes wrong, leading to a brittle or mechanical sound. Many of the worst offenders are actually tube amps, particularly, high powered pentode amps. Solid state amps that attempt to temper the artificial edginess can end up sounding a bit dull and lifeless, i.e., a tradeoff. But, realistically, very few systems can be served by low-powered amps.
For my money, if I need more power than an SET amp can provide, I would first look at OTLs. These are very fast and dynamic, but somehow, manage to avoid sounding sterile and mechanical.
That said, I can, and have lived with all manner of amps. Although I would not say that any solid state amp sounds like a good triode SET or pushpull amp, many are very good, just in different ways. I generally like amps made by Ayre and the few BEL amps I heard also sounded quite good. I thought the Hovland Radia was very good too, though, it was a touch on the dynamically dull side. I've only heard the DartZeel at shows, but, that amp shows some promise too.
I've only had limited exposure to Class D amps (Bel Canto and Rowland). I heard a $14,000 Rowland amp in the systems of two friends. While the sound was not bad, in absolute terms, it was not good either for the money. The top end seems to abruptly shut off at some point and there was something weird about the tonal or harmonic relationships (hard to say what I was hearing, except to say it sounded a bit unnatural). Still, this was an early example of a class D amp, so I would say the technology shows early promise.
