I've had this happen on some systems. It is correctable.

It is definitely a grounding/filtering issue. Go to the FAQ section of this BBS and locate the message about "What are the most common installation problems?". You will find links to some PDF documents to help you trace the fault.

Remember that the Empeg is not the component responsible for producing the sound. It is the amplifier(s). To take care of noise problems, you must look at the system as a whole, not just the Empeg.

By any chance, is your amp a cheap-o model, or is it a nice one?

___________
Tony Fabris