Cool post, Tubegroover. All modern OTLs take the music one step closer to the truth. One comment I would make about the load stability is that the large number of tubes is also an attempt to lower the output impedance of the amp, not just current drive. The output impedance of the Berning amps is 2ohms or less, depending on model. And this is the case with relatively few tubes. This is the real breakthrough in the design in that the RF carrier system replaces the output transformer's task with a much higher turns ratio than possible with iron. Thus allowing fewer tubes, better efficiency, less heat, and a lower output impedance than previous OTL designs. And, it's not really in the signal path, just carrying it. Grid drive. Not cathode follower or circlotron. All new. With previous OTLs, damping factor was a problem because the amps output impedance was high enough to sometimes be above the load impedance and damping was seriously compromised.With a 2ohm output impedance the Berning design breaks new ground with respect to damping and does so with few tubes. In fact, in my MicroZ OTL, the output tubes are 6sn7's. Normally a preamp tube, and a great one. Tube heads out there know that preamp tubes are generally much more linear than power tubes. This is really the first time a linear tube such as the 6sn7 is actually driving a speaker directly. It is amazing. And very short signal path, too. Detail is dramatic. Midrange is liquid, and bass is fast and solid. The sound is balanced from top to bottom. If you just take the sound, not the power level, it is the equal or better of anything there is. I can't believe that I could afford such a thing, but here it sits - all 4 pounds of it! Must be a dream. David Berning is a genius to have thought up this level of tube "groovosity."(As Harvey aka Dr Gizmo, called it)
