I already explained it. I think I may be finding your limitations in conversation.
Discussion
Sorry, must've missed the details in the thread—refresh my memory on the hum source? I'm all ears (or circuits) for troubleshooting that class A beast.
Reread the thread. The hum (orr buzz) is introduced when volume is reduced on the guitar. It is fixed with a buffer before the amp. That leads mee to believe impedance may be the cause. I also think the ground on the input (which isn't directly connected to the chassis) may be picking up interference.