I use a Sunfire Signature crossed over at its lowest setting (30HZ is what it says) with my SL-3s. I use this sub because it has high output, is small which allows it to be hidden behind my TV in the corner of the room, and was one of the better subs on the market when I purchased it almost 4 years ago. Had SVSs been as big as they are now, I might have gotten an Ultra instead. With MLs the most important thing is to make sure the crossover on the sub is set properly. The bass of MLs is great, tighter than most subs, until you reach 30-40hz stuff...using the sub to complement the lowest octive is your best bet.