Wayne, I have to admit that I've been lurking this site off and on for a couple of months, but I'm finally ready to ask for plans. I think that the Theater 4 would be perfect. That's about the biggest box that will fit under SAF guidelines. It looks like the different 15" motor combinations use the same enclosure? Different tuning? I will probably bi-amp, but would like to look at the passive crossover too if possible. I just got rid of a pair of mini-VOTT types with 12" EVs because the bass horns cut off sharply below about 80 hz, and I can't have THAT. They sounded better on the next block than in the house. Thanks, John