Go to partsexpress.com and look at the B&G 72" ribbons. Build it with two "wings" on either side, preferably curved or angled back like a trapazoid, with you favorite wood, and no back to the cabinet. Build a second set of boxes to the same height, a foot or so wide and deep and the 72" height of the drivers. Put four of the new peerless sub drivers in it, or maybe two active drivers and two of the matching passive radiators. Ever see the old Infinity Servo Statik's? That's what your aiming for. but for $2000 instead of $60,000 (probably $100K now if they were still available). I think Genesis had something along these lines. They give you a design for a passive crossover for the B&G's, or perhaps use an active cross over, or maybe just direct connect a tube amp to the B&G, and a solid state amp with an electronic crossover to the Sub towers. Definitely tubes on the ribbons. That's what I am dreaming of doing, but don't have the space or funds at the present!
Tom
Tom