IMO when i had (4) kenwood subs (excelon db+) I used 4 mtx thunder 2150's bridged which in mono is 325 each in a bandpass box so not knowing which kenwood subs you have the question is still in the air. If they are basic subs then go with (2) 500W (2)Channel amplifiers if they ar more upgraded and more of a comp speaker go with a more powerful amp **** as MA Audio, AudioBahn,RF, MTX Thunder