I'm doing research on which subwoofers to pair with my Magnepan MG-IIIA's.   Do you have any recommendations. 

I'm using a REL T-9 with my Magnepan 3.7i's.  It integrates quite well  but the supplementation needed in my room with the 3.7i's is rather minimal.


Too funny how I would see this thread, since I was just thinking the other day how well my Definitive Super Cube 1 was performing. 10" 1500 watt Class D. Also within my system there are also 2 Definitive Tech. 14" 1800 watt Class D subs inside my main 7000SC's. I love my music - all of it and make no assumptions about what I listen to because I'm running 5600 watts of low frequencies! (I'm giggling as I type) Response down to 11 and 13hz if I remember correctly. 

If you've ever seen the movie "Interstellar" you'll appreciate what I'm about to say. When their ship takes off from earth, my house lifts off it's foundation and separates as it travels through our atmosphere, dropping stages until it reaches space and sound drops off as my house continues to beam through space. You feel like you are floating for a moment only because the house stopped shaking!

 There is a Magellan on eBay right now. This is the most seamless sub woofer you will ever hear. It is incredibly quick because the driver is under 7 inches. But it goes incredibly low.
My system is strictly two channel audio just for music.   A booming subwoofer is not what I'm striving for.  It has to blend in with the music.  I'm intrigued by the magnepan DWM bass panel but just not certain yet.  I've done research on the suggestions all of you have given me, thanks for the suggestions. 
Zardozmike, if you want 'seamless', then I urge you to try/audition the Vandersteen subs. They are without a doubt, as seemless as you can get. I don't know where you are located, but look up Johnny R on Agon, he is a dealer who can guide you. And, no, I have never bought anything from him, but he offers his insight and experience for free.