Warren,
I do agree with you that all tube, is the way to go. I currently use a SET amp as well.
I have, however, heard a number of non-SET amps that are really good alternatives. One is a near one-of-a-kind OTL that is about 20 years old that the owner was will to part with for something like $70k. Another astonishing amp I heard was a Western Electric pushpull amp in a massive vertical rack arrangement. The owner had only one amp (i.e., mono) and cannot find another to make a stereo pair. I heard it in a side-by-side comparison with an Audionote (uk) Kageki (the SET I own). It was a better amp, but, then again, it costs almost four times what the Kageki costs.
I have heard a number of fine systems with solid state linestages in them, but, these systems are so different from mine and I cannot say what contribution to the overall sound was made by the solid state linestage. Still, some of these linestages, like the Connoisseur and the Naim 552 I heard, must be pretty good if the systems sounded pretty good.