What's below your living room? Crawlspace? If so, given that moisture isn't a problem down there you should be able to. I am no expert so I would refer you to the cult of the infinitely baffled for any further on the final design.
To make it look better you can build it into a manifold and place a vent grate over it so it just looks like a regular vent before someone stands over it and feels the deep bass.
To make it look better you can build it into a manifold and place a vent grate over it so it just looks like a regular vent before someone stands over it and feels the deep bass.