Personally, I feel DSP and it's ilk "spoils the cow's milk". I would never think to alter the eq of what the producers in the studio intended. In fact, the goal for my source gear is to preserve that source as purely as possible to feed my phase and time coherent Dunlavy SM-1 monitors, which were designed to be used with a sub. An active analog crossover is key to setting up that sub properly as is room placement etc. I do like the idea of using a device like the omnimic, but only to tune the sub with analog circuits.
Why I'm not adding a sub to my 2-way monitors for music
I've updated my blog post with more data, more analysis and the conclusion that in my particular case I do not need a subwoofer. I encourage everyone who is on the fence about adding a subwoofer or not to read and comment. I think that either way you'll be able to make more informed buying and configuration choices.
Everyone's situation is different but I hope the post helps you get to the right conclusions.