Ok folks, I am totally braindead tonight, need help. The amp IS DEAD QUIET-----=UNTIL_____ you plug in an RCA patch cord. Doesn't matter if it's on the AP, the rack or a stubbed cutoff from an ancient throwaway set. As soon as the +signal pin makes contact instant buzz, and it does not quit when the ground tangs contact the input ground surface....... F*&^%$ up input jacks???