Hi. I had a bad ground loop hum. Removing the "screw" didn't help much. I ended up buying a SUB1RR from Jenson to isolate the sub from the receiver. The SUB1RR was expensive, about $100US, but it got rid of the hum. I subsequently purchased a surge protector. It seems that the surge protector by itself also removes the hum.
Too bad I wasted the $100.


maphiker