Hey! I also have M80's with the LFM-1 sub, I also have a home brew sub that is pretty damn good. I decided to buy the LFM1 based on the reviews, thinking that it would blow away my DIY sub, but it isn't a big difference I was planning to sell the old sub, but I can't really get much for it, and I like th eway it sounds with both. So what the hell, 2 subs are better than one. Yes, I run them both, usually only for movies though, for music I only have the Outlaw sub on. There is a subtle improvement running 2 subs, its a more even bass response throughout the room. The DIY sub is not quite as tight as the LFM1. But with both of them going during movies the bass shakes the whole house, and the neighbors.