I am having a similar problem with an EP600 of the same vintage. The difference is that I have almost NO output. Gain control on both the sub and receiver is maxed out. Green light is on. Sub amp is warm. Tried using my iPod as a source, but no change. Both fuses are fine. Checked the internal wiring connections at both driver and amp. I'm stumped. It doesn't sound fried. In fact, the sound quality is fine. It's just that the volume control on the amp has two modes - off, and very low.
Anything I've missed? (Sorry for the hijack)