However, I have the sense that no amount of exacting analysis will change your mind, so here is a thought experiment. We are given a black box with only an input and an output. We test the box and find that it provides gain. How could we know whether the amplifier inside was an SE or a push-pull amplifier? The answer could be probably guessed at from a spectrum analysis of the distortion harmonics. But the decisive giveaway would the amount of 2nd harmonic distortion vs. load impedance. If the amplifier inside is SE, then that distortion figure will smoothly climb with a falling load impedance. On the other hand, if the amplifier inside is PP, then that distortion figure will remain fairly flat with falling load impedance and then sharply drop at one load impedance and then climb again with a falling load impedance. Do you want to guess what the second harmonic distortion vs. impedance plot looks like for an SRPP circuit.
   Sorry, if the tone of this reply is a little stern sounding. But you know how us guys are when rebuked. (Actually, the first tube preamp I ever built was back in the early 1980's and it consisted solely of SRPP stages. I have built and tested maybe 6-10 SRPP circuits over the years and I used to be a great champion of this circuit when few in the USA had heard of it.)
   Once again, my favorite quote from Clive Bell who began his book on art by stating, "It is improbable that more nonsense has been written about aesthetics than anything else: the literature of the subject is not large enough for that." It is tempting to say the same about what has been written concerning high-end audio and to a too large degree, tube circuits. Remember when ever someone claims to be a tube guru, ask for some math.

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