I have a box of tubes from a retired TV repairman taking up space. Some of them, I am sure, are from audio amplifiers-- and I don't see why you couldn't use a properly rated triode from the video circuit for a tube amp. If anyone is badass enough to DIY an amp based on that, I'll send them the box for shipping.
(I am really not audio nut enough to care, but I hate to see such things go to waste)