I agree with Jax2 and Tobias. Vinyl played through horn speakers with tube amplification are the way to go for things that cover the full frequency range all the time, like solo piano music, or large orchestral or opera.
Er, ah, I didn't say that. I don't listen to vinyl anymore (except in friend's systems), but certainly enjoy it. I also said nothing about horns, though I've enjoyed those in the past as well, and remain a big fan. I'm not sure I'd agree with everything you've said. I'd agree that solo piano is well served (or can be) by the system topology you propose. I'd have to say that my experience, at least with SET amplification and horns, is that it would not do the scale and dynamics of opera or large-scale orchestral music as much justice as I've heard done with other means of amplification (though it certainly can sound quite good). As far as other tube amps (push/pull, pentode, etc.) my own experience has been that the larger scale, more dramatic/dynamic music that is more densely layered seems to be better served by various SS amps I've had and or heard, though OTL tube amps have occurred to me to be a contender as well. Though I used horn loaded speakers for many years, I no longer do because of space limitations (I haven't been fond of any of the smaller horn solutions I've heard, and just don't have the space in my current room for the horns I'd like). I'm currently using Coincident Super Eclipse III's (not horns), which I like very much. Perhaps what we do agree on, and what I was trying to point out, is that one does not necessarily require high-watt SS amplification to get close to a convincing sound of piano. It seemed like early posts seemed to focus on that perfectly reasonable approach, but I thought it should be noted there are others. YMMV, as always. I don't believe there's only one way to go to get closer to realistic piano as far as the system-approach is concerned. I think everyone's version of what "realistic" piano sounds like may be quite different as well.