i don't have a whole lot of experience with the dls subs but from what i hear the ur subs are damn fine subs... i'd take them over a w6... though i don't know about the w7... anyways if you go without rears then the a5 will be plenty... i've got UR 6.5's (dls' top of the line before the iridiums came out) running off an a5 and it powers them quite nicely... your ears will bleed before you hear any distortion