I actually did try the HVL-1's with the Dayton sub. If you're interested you can read about it at
this link (scroll down toward the end of the Impressions section for what my assessment of that pairing was).
Maverick's idea is a good one; the XS15 would definitely be a better match, and with a room that's over 4600 ft^3 you're going to need more than the SUB-1200 can provide.