@atmasphere As I mentioned above, I've had a push pull SET in the NAT Audio Generator and a SET single tube in the Magma M, both with comparable power ratings. The rest of the gear and, room layout was exactly the same. I'm not an expert but I'd imagine the differences in sonic quality has more to do with just differences in tube topography but that is probably a big reason for the sonic differences. The sonic improvements with Magma M's over the Generators was easily noticeable. I've enjoyed many push pull amplifiers but after hearing the Magma M's I won't be changing power amplification in my reference rig ever again.
Regarding other tube amplification design, I am excited to see what a reconditioned Sansui 1000a receiver will do in my vintage rig. I've heard that model tube receiver was the gold standard of tube receivers for Sansui.
My tech said the reconditioned Harman Kardon 930 Twin Powered receiver he just completed for my vintage rig will be blown out of the water by the Sansui when it's finished.
Could this hobby get any more fun? I don't think so.

