Adam, the "fullness" point you mention comparing the M22 to the M3 isn't because the M22 has less bass extension, because tests show that it's actually tuned a few Hz lower than the M3. The M3 has an elevated response in the mid/upper bass which gives an impression of overall better bass but is actually slightly less accurate. With your good sub and the M22s dividing the bass range it should be excellent for the entire 20-200Hz when properly set up.
Typically in a room that isn't square, a good position for a single sub is directly in the corner near one of the main speakers.
