Just used this info to wire my HU to power all 4 channels separately. Works great! Now I can fade to the rear and boost the bass coming out of the rear speakers while using the HU's crossovers to eliminate most of the bass going to the front speakers. Sounds much much better now. The subs actually sound like they are doing something for the music in the car instead of just going along for the ride.
Thanks for posting up this info!