Here's my solution for a little thump for an old fart like myself. I had a small box with a Kenwood 10" sub, and some old school Bass Machine amp - which I am perfectly happy with - it's just enough to add some depth and bass to my Bob Seger, Tom Petty, Bruce Springsteen, Foreigner, Poison, Def Leppard, etc. (old school rock). Everyone told me that the sub wouldn't work outside of a sealed enclosure. Maybe if I was trying to rattle the dental molding off the house down the block it wouldn't, but for my tunes and my taste, it does just fine. I cut a piece of 3/4in MDF from Lowes ($6) to fit the rear and sit on the little 'shelves' molded in there. I cut the 9in hole for my one lonely sub on the driver side, wrapped in auto carpet from Walmart ($14)and mounted. I attached my little weenie amp to the underside in the center. I ordered 2 grill covers from eBay for 12" subs ($15). The grill covers I removed the rubber edging, laid upside down, sprayed with Super 77 ($7), and laid on fabric ($6). Then cut the fabric around the edges, replaced the rubber edging, and installed both grills, one over my lonely 10" sub, the other on the opposite side - so it "looks" like I have 2 and is balanced asthetically. The fabric is thin polyester that changes colors (like chameleon paint) from green to purple to blue. It was the best thing I could find to match my teal paint (there is nothing in this world that is teal - trust me, I've been all over). I get plenty of thump for my tastes, looks nice, and was cheap! Whatcha think?

Nice. In essence, you have a "sealed" box. Although I do think, the resulting enclosure area is better than what your 10" sub needs.

Might even sound better, if you were the make your shelf into an inverted 'L' shape. You know? A vertical wall, underneath the top? Keeping the top flat might be good for aesthetics, I suppose you could make the unused side as a separate section, and could make it removable, for extra storage capacity, when needed.

Yeah - there's plenty of space under there for stashing stuff - I'm going to get a 5$ softside cooler to stash car cleaning stuff in and put under there, as well as some basic tools - if I put a few rags over the tools, and stash them in a softside cooler as well, they won't rattle either (not with my little bit of thump anyways).