Why are you buying 4 channel amp? Are you going to use it for your sub? That amp bridged might be able to handle it but why not just buy a sub amp instead?
you need either a 2 channel or mono block amp. that sub is 250w r.m.s @4ohms. so look for an amp that gives out 250w r.m.s @ 4 ohms. try a alpine mrp 350. it gives out 200w @ 4 ohms, and its a good amp and a reasonable price.