Stymie,

Have you tried step 8 in your manual?

Quote:

GROUND LOOP:
If your subwoofer is producing a 60 Hz hum; remove the Chassis Ground Screw. If this does not solve the 60 Hz hum, call 1-866-244-8796 or consult the full manual at www.axiomaudio.com/manual_ep500600.html




This may take care of it.

Shawn

Epic 80/600 + M3's + M3 Algonquins + M2 Computer + EP125
I think I'm developing an addiction.