I just won a bid for a used Martin Logan Original Dynamo to add to my current Dynamo. I am going to try dual subs with my Maggie 1.6's. I got a good deal on it for $180. I am not sure that it will add anything but people seem to really like a dual sub configuration. A friend of mine just bought a second Rhythmik sub to add to his 1.7's and likes the change.

I will report back next week when I get the sub. I thought about upgrading to a more expensive sub in the $1500 range or a Rhythmik, but the Dynamo puts out really nice tight and musical bass without being overpowering. It blends seamlessly with the Maggies. Its not a great sub for HT but for 2ch music it is excellent.