WARNING: Tube/Valve amplifiers use potentially LETHAL HIGH VOLTAGES.
Building, troubleshooting and testing of these amplifiers should only be
performed by someone who is thoroughly familiar with
the safety precautions around high voltages.
May be best to keep the voltage around 800 volts and high Ma's for best sound.
I used a circuit for 811A's PP. The Se ones I have heard that run close to 1000 volts sound very poor.
Phil