PL519 Amplifier ...modify to Cathode output typology for nice matching w SPK

ref. typology

select signal tube 6922 vs 12Ax7

6922 Left channel

                                                12Ax7 Right channel 

take off PL519 40V heater transformer

for 6DJ8 6.3V heater 

make sure the -Voltage for gride bias

add 1st 6922 tube sockect

DAC feed in 1K wave then transfer to analog 1Khz waveform

1st stage 6922 gain tuning to balance p-pV

2nd stage 6922 gain p-pV w offset