jamato8
Headphoneus Supremus
I have found that while tubes can be forgiving and you can use with an adapter, which I made like 12 years ago, a 12SL7 in place of a 12AX7 and a 12SN7 in place of a 12AU7, if bias and plate voltages are "really" optimized, you are not going to hear the truth of what each tube can deliver. I have used the 76 and only after getting the bias and plate voltage exactly tuned, the sound wasn't everything that the 76 could deliver. I used high quality pots and then replaced them with good resistors. I also found that battery bias, IMO, is better than anything else.