Mojo, I know this. Running the jumpers from the speakers to the sub ensures you are getting proper phase easily.

In fact, doing so with the subs next to the actives, driver facing the same direction as the triple 6.5's, will make for a full range, flat to 17 Hz, phase correct system.

A great disc to demonstrate what the EP can add would be on Steely Dan's 2 Against Nature CD.

The 2nd track has a 16 Hz synthesized kick drum that hits both 16 and 32 Hz.

With the EP800 in the system, the deep bass ripples through you. Take the sub out, and you still get the 32 Hz hit, bit without that ripple effect that 16 Hz adds.

You are experiencing what you are due to a lack of content below the mid 30's.

A properly dialed in sub should be unnoticeable until the rare time you get bass in the 15 to 30 Hz range.

Your content and upstream equipment may have you in a position in which a subwoofer doesn't add much.