I am having in a similar situation as yours. For some reason, the output of EP500 doesn't seem to be putting out a lot. This could be with my receiver and source settings.

One of the experts at Axiom told me, to test out the output of the sub, you should put the coaxial cable of sub to the audio output (where the composite cable (either red or white) goes to the DVD player, and play a track on it.

Let me know if enough output comes out of it.