the single amp would be plenty... get a single voice coil 2 ohm sub and you'll get more power to the sub, for cleaner sound. That 5 channel amp is a TANK, my brother has it running all Boston speakers, components in the front and 6x9's in the back... with 2 10" Boston competitor subs and it rocks...

If you want it simple, go with the 5 channel... it'll give you PLENTY of power and it sounds amazing! Save the $100... plus some... you only need one 8gauge power wire, instead of a 4 gauge with a distribution block... and a smaller fuse... saving you more money.