So you are in search of a good sub? There are a number of good options available. One option that is convenient to the forum is to go with an Outlaw sub to keep your 990/7125 combo company.

Your room is a bit larger than mine (23'x17'x'8), and my original LFM-1 handles the space very comfortably. You could look at an LFM-1 Plus for $550 or one of the new LFM-1 EX's for $650. You might also look at the specials that were just announced via e-mail this morning: an LFM-1 EX/SMS-1 combo for $999, or an LFM-1 Compact for $339. Aside from having a few less dB of maximum output, the Compact offers specs that are very reminiscent of my LFM-1.