There are several suggestions above that would not likely have you wanting for a sub (I can speak first hand for Daedalus and Coincident). If you are going to go that direction I'd second the suggestion you go with more than one sub, and would add to your short list of speakers to audition, AudioKinesis, who do offer a wonderful implementation of multiple subs (Duke's "Swarm" system) in some of their speaker offerings. Outstanding and seamless integration of low frequencies via multiple subs, assuming that's what you are after. To keep it simple, with fewer boxes, some of the suggestions above are able to reproduce fairly low with control and integration. Right at your stated budget a Daedalus Ulysses would make a sub mostly redundant, but for the most demanding bass heads.
