if i were you, id take the easier (which may possibly the best, maybe not) route,
get a passive signal y adapter, or if you have more amps that all have the sound yer lookin for get a 4 way or somethin... and split the signal from yer bass or pedals, and run a seperate line into each amp. then set the cabs up to match the ohm rating on each amp.. and figure out with cab sounds best with which amp. not only can you get a shit load o' power from each amp, but you can also set the tone seperately on each amp and have a really full sound... you can use whichever amp you prefer for the low and high.. theres a lot you can do with this... i dont play really loud much, but when i get an itch to rattle the house with some heavy drone, its done the trick... ive never done it live and am not currently playing with a band, i wish i gave it a shot before. but try it out, you can probly figure something out that will beat the shit out of everyone who hears you play...and if it works out right, theyll like it.