I notice HiFi World have a respected classical musician writing for them on a regular basis. Rafael Todes is the second violinist with the Allegri String Quartet and seems to be a well informed audiophile. His reviews state that he uses valve monoblock power amps and I am coming to think he's probably wise to keep clear of solid state power amps (at least with regard to good reproduction of classical/acoustic music).
I've just reinstated a pair of Electrocompaniet AW180 power amps into my system and they have excellent bass, a silky smooth treble, great control, etc. Having also tried other power amps made by EC and also Classe power amps I always come back to the same observation - they are initially excellent but after a while they seem to lack a 'thickness' of sound that is of such importance to the reproduction of say, orchestral string tone or brass timbre in the midrange. The sound I'm getting with these amps is appealing but I have to say it's not a 'natural' sound at all. Indeed, my Quad 909 does a much better job of reproducing a full bodied string tone etc. This is not a feature of my speakers as I'm using the earlier Sonus Faber Cremona, which is known for its warm sound. I've also tried different front ends and preamps, so it seems to be a function of big, powerful solid state power amps.
Perhaps I should sell the Electrocompaniets and take the plunge with some hefty valve monoblocks; I notice some wammers using Icon Audio power amps seem to be very happy.