Hey-Hey!!!,
Sorry, I must disagree with the idea that a good OPT is only going to really benefit a DC SE amp. Not my experirience. I have found that PP requires the same sort of consideration. Even for measured paramenters like leakage L and capacitance. It is not just OPT's, other signal Iron is also very dependant on its construction details for excellent sound. Good sound is easy. Four triodes, two or them low mu power valves like 2A3, a good OPT. With some careful design, and implementation, we can make the leap to excellent. We could just as easily start with EL34, 1619, 807 or 13E1...
regards,
Douglas