i've got a 2 amp system. an alpine 3547 is bridged to pump 180wrms to my 8"er polk momo. an MTX Thunder 564 gives 70wrms x 4 for the other speakers. my sony F50M HU only has 2 preamps - front and rear/sub. i'm using the rear/sub for the alpine. what do i do for the MTX? can i run the front preamp and split the rear/sub?