Mark,
It could also be something coming into the preamp. I would unhook everything from the preamp except the AC power cord and the output cables to the amp. This would be like starting from square one.
If you hear any noise, it is either the cables from the preamp to amp or the preamp itself, (probably a tube).
If you do not hear any noise, start plugging your components back in to the preamp ONE AT A TIME and listen for the noise. One of these will be the culpruit. Which, now you will need to determine if it's the unit itself or the cables from it to the preamp.
Sorry, but you'll need to troubleshoot this thing from the very beginning. I just helped a friend do the same thing. Noises/hums/buzzes are a pain in the ass to find. Starting from square one and working one at a time is the only way to find it.
It could also be something coming into the preamp. I would unhook everything from the preamp except the AC power cord and the output cables to the amp. This would be like starting from square one.
If you hear any noise, it is either the cables from the preamp to amp or the preamp itself, (probably a tube).
If you do not hear any noise, start plugging your components back in to the preamp ONE AT A TIME and listen for the noise. One of these will be the culpruit. Which, now you will need to determine if it's the unit itself or the cables from it to the preamp.
Sorry, but you'll need to troubleshoot this thing from the very beginning. I just helped a friend do the same thing. Noises/hums/buzzes are a pain in the ass to find. Starting from square one and working one at a time is the only way to find it.