what else can be used as a driver tube and may i take a peep inside??
I'd suggest hi-current/low-impedance tube

6BL7, 12B4A and 5687 but those tube need another voltage driver stage before that.
I once used 6EM7 with zero bias of 811-10. Then I tried it out with low volt - high current style (811-10 was run at 450V 150mA!). These are A1-A2 experiment. I still have few ideas to try with 811-10 but haven't got time to do yet.
may i take a peep inside
Here's