what you should find out from cadence is, if you can use (2) channels 150x2@4 and then bridge channels 3&4 for 600 to a sub. that imo would be ideal. if you're going to run a sub, inboats and tower speakers, imo you need 2 amps.
did you buy that cadence already? you should also be warned some of those had issues with overheating. i don't know the hole story, but i know i ran accross it in the BU forums when i was reading about amps and wetsounds. rumor has it, that's why they had them for sale on their site for b-stock. they redisned the heatsink fins and a circuit iircc.
2003 X-2 MCX