Tim - I hate to keep flogging this horse, but if you get the opportunity to hear them, the Vandersteen 2Wq subwoofers should solve your issues quite nicely. Unlike most mass-market subs, they are designed to go into a corner, on the floor. In my case, after years of tinkering with a Def Tech PF15 subwoofer (including moving it around, adding a Behringer 1124P parametric EQ and a Paradigm X30 sub controller), I finally got the Def Tech to be somewhat unoffensive for music and useful for films. The Vandys, which I bought two of, used, worked perfectly in the first and only location I've had them in - the front corners of my room. These are not "bass freak" subs; they are accurate, musical subs that will produce tuneful, extended, clean bass, and plenty of it, but only when the music calls for it. Best of all, now that I have the Ohms, I can attest that the 2Wq blends seemlessly and easily with at least the Ohms and Vandersteen mains. I suspect they will blend well with most loudspeakers that are solid down to 40Hz. I urge you to check them out at the Vandersteen web site, since the design concept and connection scheme is a bit different than the usual subwoofer. I would guess that, if you only need a sub for the center and surrounds, the home theater version of this subwoofer would suffice, but I haven't heard it in a long time, so YMMV.
