What subwoofer to use with Maggies?

Thanks for the suggestions to this point. I am using a Earthquake MKIV-10 with both a passive and active 10 inch sub. The subwoofer is placed in the back of the room close to the couch. The Maggies are on the front wall, or more spefifically about 36 inches from the front wall. My issue has been one of constant changing of the subwoofer level. Just when I think it is dialed in on music it lacks in base for movies, then once dialed in for music it lacks the authority for movie soundtracks. I agree with the above comment to keep the woofers smaller, I was thinking a pair of 8 inch subs but have noticed that there are not many offerings in this category. I also like the sound of the 10's as they seem to be a solid mix for both music and movies, but obviously I am not thrilled with the performance to this point.

Tpsonic

Yes, a Sunfire Theater Grand II 5.1 processor and a matching era Sunfire 5CH amplifier. About 70% of listening is 2CH stereo, the remainder is 4.1 as with the Maggies I just don't 'hear' the need for a center speaker. I just don't feel the Earthquake subwoofer blends correctly with the Mag's. For movies it rocks without question, maybe it is just not musical enough or a fast enough sub to keep up.

Has anyone had any experience with rythmic audio subwoofers. The spec sheet reads like that of a $7,500 subwoofer, servo control, killer extension and the cost is amazing when one looks at the performance of other subwoofers costing much much more. My knowledge tells me that the servo is going to address the issue of keeping up with the Maggoes and the low mass driver and overall design of the rythmic at least on paper seem to state this is one killer subwoofer that can hang with the giants.

I do agree that smaller can work but my fear is that to get low extension one is going to need multiple smaller subwoofers to get to a decent level of sound.

The other clear winning point of the rythmic subwoofers is the extreme low distortion. This has always been an issue for me when using other subwoofers, Sunfire, Velodyne and the majority of the big names in sub's all scream about the output and the massive amount of sound, but it seems to come at the cost of huge levels of distortion. Wall moving base is great but not at the cost of 10-15% distortion in the reproduced sound.