Ok for this box what 15” driver would work best for my home theater for under $500 Klipsch KP-115-SW-8G . It is 24.5” tall ,19.5” deep, 19” wide. it has four 15" ports in each corner and the area inside is about 5.11 cubic feet or 144.87 liters. All my speakers are Klipsch I have KLF 30's for the mains and my center is a Klipsch C-7. Let me know what kind of driver you guys think I should get for it,and also where to get it from, and any other words of advice.