The Pioneer 1020 should have half-way decent standing wave attenuation.
If you're in the mood to tweak try this:
Get the receiver to produce the pink noise on the sub-woofer channel. Use an SPL meter very near to each sub (like less than 1 foot away from the cone), so the influence of the others is minimal, set them all to the same output level. Now run the multi-point standing wave analysis selecting three points in the listening area (they'll be in the order of 2nd, 3rd, and then primary). Check the that receiver's sub output level is 0 or slightly positive (if it reads negative go back to the first step, and adjust each sub to a lower level).
That should get you even output, and the receiver will be killing 3 of the boomy frequencies (usually standing waves created by the length, width, and height of the room).
