Amp was made on 9-30-13; seller claims
"I once asked Dennis if I could put a tube in, I can't remember which, and he said stick it in. If it works, yes, if it doesn't, no." and "I have used the 300B output tubes, and have a set of Valve Art tubes to go with it."
I thought 300B requires totally different circuit/voltages.
Seller gives pentode power ratings for other tubes.
