I took another look at the SA-1000, it looks like it might be a better choice than the SPA-1000, and on the back of the unit there's a toggle to turn the on/off the subsonic filter, and I was also mistaken about the PEQ, it's 18-150, like it's plate brother.
I had heard about the iNuke, the problem is that I did some research on Behringer and apparently they're not very reliable, whereas, the Dayton audio gets rave reviews when I read about it. I would probably go with two of the Dayton Audios. Since, I do have two LFE pre-outs (7.2 channel).
I wanted to ask, though, would a vented sub-woofer box work, like 7.2 cu. ft., the vent was roughly 12 inches wide by 3 inches tall? I saw one unfinished (no carpet or anything) at a car audio place, I thought I could veneer it or build an exterior box for it out of birch and then stain it. Or, are those boxes not recommended for home audio, I would imagine the tuning frequency is probably a little high, since car audio applications typically rely on cabin gain.