Thanks Larry for sharing about the massive OTL amp from Greece. Very interesting!
Whenever I read one of these SET vs. PP threads, I am always left shaking my head. There is just so much more to the sound of an amp than this one aspect. Most of the time people are comparing very different types of amplifiers and they then ascribe the differences to the SET/PP aspect alone. It matters quite a bit what type of tube is involved. Among the directly heated tubes, the 211, 300B, 2A3, 45 and 46 all sound quite different. Then there's the matter of input and driver tubes and circuitry, all of which can sound quite different. The output transformer is very important. Then there's the power supply---solid state vs. tube rectifiers, type of supply filtering, regulated or not, do the directly heated tubes have AC or DC filament supplies? And we are not even scratching the surface of component differences---every capacitor, every resistor, every wire has some effect on the sound. Plus all of these issues apply to both the SE and PP amps.
The bottom line is that amps sound different for many reasons, only one of which is whether they are SE or PP.
In my case, I have 3 pairs of monoblocks, two PP and one SE, and I rotate them in my system every couple weeks depending on my mood. They all sound excellent but in different ways. None is categorically superior to the others.