That seems pretty nuts. If you want some more low-end oomph, I can see goosing up the range below 30Hz by a few dB. That should do the trick. 20dB of boost in infrasonic ranges is crazy. I guess you could try it. The problem is, you probably listen at a louder level than 75dB, and, while your subs do have a nice amount of headroom in deep bass, they don't have infinite headroom, and a 20dB boost below 20Hz is asking a lot of any sub system.