Hi Wolf,
Incidentally, on that note I live in Pass land. :) Threshold, Pass, XA, Firstwatt, all around me, everywhere here. Along with competing AudioNote custom tube amp builders (battle of the amp builders..hahah) Grew up working at the same speaker factory back in the 80s where it all kinda started..., prior with Dr. Von Heil (FET transistors). My grandfather worked on those FET projects back east too, in-depth. For one, i'm truly amazed at what Nelson has managed to do and how "close" he gets with transistors. Agree on XA25, maybe more so than SIT-3. More recent proof in getting closer is his recent DIY stuff with "NuTube", tube is tube. Look up NuTube DIY preamps if you have not done so. He is no stranger to tube :) Transistors is just what he does, well.
Even tried some of DH Inspires as a follow-on to some earlier Triode Cary stuff. All done with that now Achieving the right combo of tube power with dynamics has been the goal for me (with my particular cutsom designed hybrid electrostatic speakers), much closer now with local design dual mono amps. Back to pentode now - not triode. With the right bias, the right triode input tubes, pentode power is hitting the sweat spot now for me - lush with notable dynamics while retaining deep wide sound stage. Build all my own speakers past 40 years. I run dual custom built Scanspeak solid state powered subs myself, very musical too. Good fun!