I would think this is a room issue as well but you would think that you would hear some good bass somewhere in the room huh? If a driver is faulty, you wouldn't think that this would be the case with all woofers. Do your m80's have multiple binding posts on the back?
My living area is large, but not on the same scale as yours (which I would classify as huge). For reference, In my living room (17.5 x 21 with 12 foot ceilings), I find the m80's to put out plenty of bass. My room is also open to a kitchen with 9 foot ceilings. That being said, even with my room I find the ep500 necessary, and in all honesty feel like I need a second sub for movies to smooth out the bass response and add a little "oomph".
I wonder if the shear size of your room lends to having a dedicated 2 or 3 channel amplifier to obtain the punch you are looking for?
I will add that you have a beautiful looking room as well
