Thanks for the reply. I've sent the amp and the preamp in for repair already once. But the problem is still there.
Also, I think I'm seeing a correlation between when it rains and the buzz. Note, the buzz is not always there. Some nights (when I am using it) there is no buzz. Could it raining have anything to do with it? Like a improper ground outside and when it rains it causes issues?
If you are right and its a capacitor, what would be the most likely culprit? The Amp or the preamp?