How do you know when preamp tubes go bad?


Over the last few days the sound quality of my system has diminished considerably. I'm using a tube preamp driving a SS amp.I've seemed to lost a lot of my my soundstaging.Any input would be greatly appreciated.
mfb33

Showing 1 response by sidssp

I read somewhere that Victor at BAT said an old tube can be reactivated by feeding it a certain current at certain voltage. Does anyone know how to do that?