Simple question: If I want more power to the subs under the seat, can I tap the signal from the cables that goes to the sub, wire them to the trunk, amplify through hi-low level converter and amplifier, and then back to the subs? Or will I have to get a sound processor and do it the "right way"? Is the level filtered both front and rear?

I have business stereo, no amp in trunk.

PS: The WDS diagram on e60 shows the front midrange and subs wired in paralel with each other. Isn´t that strange?