What subwoofer to use with Maggies?

I am usingf a REL T-2 with MMG's. I'm very happy with this combination. My room is 12x12x9. If your room is larger or if you want more base you could move up to a T-3 or "Storm". I mainly listen to classical and Jazz.
In two weeks I'll be sending my MMG's to Peter Gunn for his highly regarded modifications. This is reported to improve and extend the bass of the MMG's.

Keep the woofers small,in multiples.I would suggest using a 6db/oct crossover into the MMGs.Will you be bi-amping or passive?Can the woofer assembly be placed in the same "plane" as the MMGs or possibly used as a base?
If a box can be built,the Audax Aerogel 8" drivers are being cleared out at $25 a pop.Their efficeincy is 89 and might be used in a passive arrangement.

you will need a high quality sub no cheap home theater subs
I recommend REL's highre end subs, Bag end or ACI All are fast enoughfor the Maggies and very smooth to blend in

the new Rel smaller subs, mabye 2 depending on room size, or a Velodyne DD-12. I have an SVS cylinder that I love.

The JL Audios are excellent, and bit on the higher priced side.