OK, I had already tried all suggestions except hooking main speaker wires into high level input (& yes left to left or right to right) and it was also plugged in! Still nothing. Did same with Sunfire & it worked. Next i removed the eight (8) allen screwes & gently pulled the driver out & found every wire to be where it is meant to be. There is slack in wires from box to driver this may be what i was hearing. could'nt have been anything else. I looked everything over inside cabnit. Went to local dealer & asked for cable so I could run my sub. Already have what he gave me. ( No I didn't buy it anyway) Power on light on back of ep500 is on, levels on sub & receiver are turned up, set speakers to small. The ep500 has no hum what so ever. It has not made so much as a whisper.
