A solid-state circuit using an NPN and a PNP similar in configuration to a solid-state class AB power amplifier. Kind of defeats the purpose of an all-tube preamp or line stage. Single ended input to me would be the purist approach and the fact we're most likely to use short interconnects and noise wouldn't be a factor as in long ones.
@faustuss The amp I was describing in my prior post is a tube amp. Its very compact and makes 5 Watts/channel class A. It has 3 tubes per channel, the same number you would have if driving the power tubes with a conventional (not balanced) Voltage amplifier/driver circuit. The parts count is the same.
If you meant something else by your comment it went right over my head.

