Hi Kenny,
Generally speaking, the PSET approach will get you more power, but, not the same amount of power that one would get by using the same kind of tube in a pushpull configuration.
Also, how much more power you would get with two output tubes vs. one is somewhat unclear. As Charles1dad has mentioned, there is the issue of the tubes not working identically. With my Audionote Kageki amps, I have noticed that after more than a year of operation, the two output tubes per channel will test quite differently, particularly for transconductance, when I test them on my Amplitrex tester. Whether this IS the result of the kind of imbalance issues that are claimed for PSET designs, or is attributable to something else, I have noticed this "problem." The amp will still sound great even when the tubes test very differently, but, with one tube being much weaker than the other output must be lower than before the tube started getting weak. I don't need much power, so that might account for why the amps still sound quite good. That the tubes in both amps would test so differently initially bothered me a bit, but, I "solved" that problem by no longer testing the tubes.
