I have 4 amps, all on the same outlet: - 65 Fender Tremolux - 74 Fender Princeton - 80 Fender Princeton Reverb - Dr. Z MAZ 18 Jr. The Tremolux, Princeton and the Dr. Z are dead quiet when turned on and plugged into. The Princeton Reverb has hum with nothing plugged into the input, and hum goes up with volume. Hum increases as reverb is turned up. I took the Princeton Reverb to rehearsal yesterday, and it was dead quiet... This is an issue that's tough, as if I take it to my amp tech, it will be quiet as well... I've even tried plugging the Princeton Reverb in to a Hum-X isolation transformer with no change... Any thoughts? Thanks!