Bill, I highly doubt it. The BagEnds are designed with the processor and the box/driver as a unit to work optimally. Simply adding a variable filter to an existing box that has it's own designed in performance tradeoffs will likely result in lower performance and or damage/reliablity issues with the driver from overdriving at low frequencies. You might luck onto a setup that works, but I doubt it based upon a lot of years building, designing and modifying amps and speakers. To do a speaker box that does a true 30Hz for low B (or even 40Hz for E), at decent levels with a clean sound and efficiency means a big box; laws of physics and all.....
