What is best sub to match with Magnepan?


I have the Magnepan 1.7 speakers. I am looking to buy a sub in the near future to pair up with them. Since the planars are fast, I need a sub that is VERY quick. I have a Sunfire sub, but it is not doing the job. Can anyone recommend any brands/models that will work well with the Maggies?
BTW, I'm on a budget too. Trying to get the best bang for the buck.

Current set-up:
Denon AVR-4802 (will be upgrading, not sure what yet)
Olive 03HD music server
Emotiva XPA-2 (500w @ 4ohm)
Sony Blu-Ray player (will be upgrading to OPPO BDP-105)
Magnepan 1.7 Planar speakers
Sunfire TS-EQ10 subwoofer
lsbklyn
Miller and Kreisel larger 12" sub i have mated with my Maggie mmgis..The system is awesome...Deep top quality bass..it turns the Maggies into monsters,,,Driven by ACURUS 150 amp and pre R11.....and a refurbed ARes-1 table with a VINCENT 08 phono pre amp...as awesome as this economical system can be

The Rythmik f12 is a fast sub, crossed over at 60/70 hz.. I think with some tuning will  work well. It will also open the Maggies up as the amp driving them , I know impedances can vary and one the reason high current amps seem to gain power in the low end. I guess it may depend a little on what type of music you tend to enjoy most. Is there information down in those lower fundamental notes that you want to hear.

One comment from someone who has owned Maggie’s for the last 15 years, before spending another nickel on anything, get MYE stands.  Unquestionable the biggest bang for the buck in system improvement.  Check out the planar asylum for confirmation.  Best bargain I have found to help your system!