I've had Vandersteens for over 30 years. I've had the pleasure of phone conversations with RV and met him many years ago. He knows of what he speaks! John Rutan at Audio Connection has a more congenial manner than RV and as has been said here, knows what's going on with Vandersteens and system set-up. In my 13'5" wide, 18' long 7'6" high dedicated room I have a 2wq behind each Treo CT in the corner! Once you get them dialed in, specifically the efficiency of the main speakers so the subs mate perfectly you are good to go. I think your room should be able to accommodate two Vandy subs.
If you want a useful chat about the issue, call John at AC at 1.973.239.1799.
Good luck!
If you want a useful chat about the issue, call John at AC at 1.973.239.1799.
Good luck!