Hemi,
I would recommend you get floorstanders that require no sub. But, if you must go with a sub, then research dictates that you get two subs. Otherwise, no matter what sub you get, you will always be able to hear that the bass is coming from where your sub is placed. THis may not be a bad thing for you, although it was not the sound I wanted. Since I did not have space for two subs, I finally was able to get floorstanders. I tried the following subs: B & W ASW 675 and B & W ASW 750 and the top two Martin Logan subs Depth , and Descent. The 750 and the Descent were both very good subs IMO.