LED's in the cathode..

[SY]

No reason why not, but if you direct couple from the plate of the previous stage, the bias sets itself from the size of the cathode resistor and the voltage amp's plate voltage. No need to do anything else.

 

[cyclecamper]

Choke and caps in the power suppy filter ladder, LEDs on the cathode, inductors for the grid bias, inductors between anode and B+. The only resistors would be pots.

Now if I would only drill the keyed center pin in the output tubes and get the LEDs to shine up thru the tubes. That would make my guitar amp impress the kids.