Hello,

The listening area you describe is only about 1232 cubic feet. (assuming a 8 foot ceiling). Not that large.
A good 10 inch sub would most likely suffice, although a good 12 inch would provide a more foundation shacking experience. Shake it up if your budget allows.
(you can never have too much sub, as you can always turn it down).
Maybe a sub can be to big, some can be massive phyically
Enjoy \:\)