Eric, based on what I've heard today in a 13x20x8 foot living room, I now believe you don't need a sub with the M100v4. And the goodness doesn't stop with the incredible bass. They were made to be placed on the short wall in such a room size. Wow. Just wow!

House of the Rising Sone
Out in the mid or far field
Dedicated mid-woofers are over-rated