I recently purchased an MB Quart ZA2-1000.4.... It has two x-overs one for channels 1&2 and one for channels 3&4. It is also bridgeable. My question is can i use the lowpass x-over for channels 1&2 and bridge them, to run a 12" sub. Then use the highpass x-over for channels 3&4 and leave them unbridged to run two 6x9'S. Or do they all need to be Bridged.. Or all need to be unbridged. Thx in advance for any help...