I have an eighteen inch subwoofer I will be using in my home theater. I made the box (5cuft) and ported it to 25hz. All I need now is an amp to do the dirty work. I looked around and I cant find any amps that would put out the power I need. I started looking into concert amps and found a Behringer EP1500. The only bad part is it doesnt include a low pass filter. My question is where are the high powered sub amps for the house or where can I get a good passive low pass filter? Thanks in advance!