You keep hanging in these parts and the crazy becomes the norm. With the MBM, you have a driver typically pro with a light cone, low inductance, high sensitivty and you implement it with your Mains or a split lfe. With your Mains you need an external crossover and the MBM plays lower than the Mains but not lower than the lfe. Hsu research an MBM and the range is 50-150hz. When used in a split lfe configuration, you'd have subs that are most capable for ultra low frequencies but don't extend very well into the midbass. In that scenario the MBMs would take over from the midbass on up where the bottom dweller subs don't do so well, again using an external crossover.