Pass Labs XA30.5 and ModWright KWA150

OP, if tubes are out of the question for you, I would go with the Pass XA.5, it really does not get better than that if 30 Class A SS watts is enough to drive your speakers.

Like Zybar, I have also tried Atma-Sphere amps with and without ZeroFormers. The amps were M-60 monos and the speakers were Silverline Sonata III. Unlike Zybar, I did not find the improvement with the Zero/M-60 combo to be preferable to an entirely different amp (which happened to be a solid state model). The differences were substantial. I also tried the ZeroFormers with the solid state amps as an experiment, and I still preferred the system without the Zeros.

ZeroFormers are something that are system and listener dependent, IMO, which makes the Speltz home trial offer valuable.

All good points Tvad. I tried the Speltz Autoformers with the following speakers:

Vandersteen 5A's
Emerald Physics CS2's
Omega Revolutions (8" Alnico driver)

Ultimately, trying things at home is always the best course of action.

George