For what it's worth: I bought one of the used 120S models here on Audiogon. I have not had much chance to experiment with the sound (I'm between preamps) but I have used it enough (with a loaner preamp) to speak to the heat issue. As tube amps go, mine does not seem to get inordinately hot at all. This amp is much less hot, for example, than the Six-Pac monoblocs I once owned. Of course it does get somewhat hot, as one would expect an 8-tube KT88 amp to do. But not unexpectedly so.
I'll report more on this thread
I'll report more on this thread