I have a B&K pro 10 mc with separate power supply, I tried balanced XLR, and RCA cables, still the same hum, I tried running the cable tv line through a conditioner, still the same, ....now....where did I put my sledgehammer, I hate when this happens, i have checked and double checked every damn cable in the system, speaker wiring, amplifier cables, power cables, touching, not touching, still the same.