@almarg That’s interesting to hear, Roger. Although to be precise I’m pretty certain that the 8 and 8B were both single-chassis stereo amps.
I’ve never heard an 8 or 8B but during the 1990s I owned a pair of Model 9 monoblocks and a pair of Model 2 monoblocks. And I greatly preferred the sound of the 2s to the 9s, although in fairness I can’t exclude the possibility that condition may have been a factor in that.
The 2 was similar in some respects to the 8 and 8B, which came later of course. Although in addition to being monoblocks the 2 employed tube rectification, while the 8 and 8B used solid state rectification, and the 2 used 12AX7 input tubes while the others used 6BH6s.
I’ve commented here in the past that at least when used in conjunction with speakers having benign impedance characteristics and not requiring more than the 18 or 20 watts or so that the 2s were capable of in triode mode, in that mode the 2s were one of the best sounding amps I’ve ever heard.
I never got my hands on a 2 but I studied the 5 (half of an 8) in great detail and I saw how they did the tertiary feedback winding. I had to do a lot of experimenting to make that work out but its a trick I have rarely seen in other amplifiers.
The separate feedback winding makes the amp more stable into reactive loads. Perhaps few know that we made all the transformers for the RM-9. I cut my teeth on the design of that output transformer.
The 9 was quite a departure from the 8, far more complex, perhaps better specs, but when you take specs too seriously (as in too much feedback) things can go downhill.