What is best sub to match with Magnepan?

What is it about the Sunfire that's "not doing the job" specifically? Are you having integration issues of some sort? I ask because I was able to integrate 10" driver Sunfire subs very successfully with Maggie 1.6's. The Sunfires were not last word in performance by any means, but as long as the level, phase, and crossover points were set properly, I never felt they called attention to themselves and definitely helped to fill out the lower octave. Is your system two channel or are there other speakers in use for Home Theater functions?

I don't like or use subs (I say upgrade the speakers/amps, but understand may not be feasible/practical & you may really like what you have) but the rules I have always heard (as subs are so tough to integrate properly) is (1)buy the most expensive sub you can and (2)get one with an included bass amp as running a sub off your amp is pretty much a mess. That bottom bass octave is the toughest to get right and it will cost you. There is music down there! Remember, good bass frames your soundstage.

(you may not be liking the bass because if your amp but I do understand the maggies can be a little bass shy (the 1.7s)).

Good luck.

Here's a thread from a few months ago on the same topic:

http://forum.audiogon.com/cgi-bin/fr.pl?cspkr&1382555455&openfrom&1&4#1