Figured I'd give you guys an update. I finally removed the sub from the cabinet and started playing with placement options in the living room.....and it sounded great in the living room when sitting next to either of the front speakers, but I had nulls in certain seats that only a second sub could fix. I figured I would try my other sub (ED A2-300) and see if dual subs would work, and it did smooth out the bass for all the listening positions. The only problem was that the ED was a lot more powerful than the sb12 with LFE, and you could hear an imbalance with the volume turned up. So last week i stumbled upon a craigslist ad for another A2-300, and i finally picked it up today. I haven't hooked it up yet, but I think once I set them up and calibrate them, my bass needs will be met! I'm going to hold off on the HSU or PSA until I get an upgrade bug again...but I know i'm probably going to stay ported from now on.
Thanks guys for all the help!