[Wayne A. Pflughaupt]

Another option would be to get an analog pro-audio electronic crossover and install it in front of the Behringer EQ. I think this would work better than shelving. A shelving filter will only drop and then flatten the level by the amount you cut it, not infinitely like a low pass filter will. The crossover will also have level controls to maintain a good signal for the EQ and amps downstream. An ouboard crossover would also allow you to keep an 80-90 Hz setting on your receiver for your main speakers, which you probably want.

The Behringer CX 2310 is probably ideal for you. It has a dedicated subwoofer output that you can set as low as 10 Hz. So you can set in anywhere you need to tame those upper frequencies. You could even cascade the mains low pass on top of it, if needed, for additional upper bass signal reduction. You can find the 2310 for pocket change on eBay.

Regards,
Wayne