One or two subs

A friend of mine does audio and home theater installations and used Sonus Faber and REL equipment for such installations. If budget permits, he always went with multiple subwoofers. This is done not to preserve the stereo/multichannel effects, but because it is MUCH harder to get even bass response in a room with just one subwoofer. Unless the room is really big and you like to really crank it up, two smaller subwoofers would be preferable to one really big subwoofer.

Whether you have one, two or more subwoofers you will have cancellation/reinforcement from the waves reflecting off of the walls, floor and ceiling. The various nodes of either reinforcement (where the crest or trough of two waives meet) and cancellation (where the crest of one wave meets the trough of the other) are most severe with ONE subwoofer. Having multiple subwoofers creates many more such nodes so that any particular listening spot is subject to many of such interactions so that any one interaction is not as severe in effect. This is the primary reason to use multiple subwoofers--actually creating many more of such cancellations and reinforcements instead of fewer and more severe wave interations.

Kalbi23,

You don't have to take my or anyone else's word on the subject. Just google "multiple subwoofers in a home theater" and you will find that most experts agree on the superiority of that approach. Multiple subwoofers makes it possible to have much more even bass response throughout the room.

The issue for you is whether it is wiser to spend more money for a bigger/better single subwoofer vs. buying multiple cheaper subwoofers. That is a more difficult choice. Most listeners would find that a single bigger subwoofer will give more impact (hit-you-in-the-gut effect) and deeper bass, but multiple smaller subwoofers gives more even coverage, better pitch definition and better overall sound for music reproduction. If you place a high priority on impressive home theater sound effects, the bigger badder woofer would probably be a better choice.