The only problem associated with running 2 of the 4 channels to power your subs is that you're not feeding the subs enough juice. In order to get the bass you desire you need to power the speakers with plenty of wattage, therefore I suggest going with maybe a 2 amp setup. Get a 2/1 channel and a 4+ channel for your speakers up front (depending on how many speakers you have, I didn't notice if you had rears installed). That way you can properly split the juice and get the most out of each of your speakers. If you can get a hold of RF or whoever you're interested in, have them send you a brocher. They'll have all the specs.

 

IMHO 200 watts to the sub is plenty...

Dinnyin