diytube.com

I'm trying to get into working with tube amps (I've mostly done micro-electronics up to this point) and have an old califone promenade lying around. From what I've read on a related post here, the promenade has the guts to make a pretty good guitar tube amp head.

However, I can't find a schematic online and have a bunch of other questions regarding what to remove, what to add, etc.

For example: I'm getting a buzz and a bit of high pitched noise. Should I replace the caps on this thing?

Additionally, are the microphone inputs high impedance? I assume they are...