In that case, I've got a couple recommendations:
1. If you haven't already, build a cardboard mockup of the PB13U to get a better sense of the size and how it will fit into your space.
2. Give the XS15se I mentioned earlier (times two) a second thought...and a third. A pair in a <2000cf room would make for a very capable system. If you can up it to a pair of XS30se's, better yet