No, just 3. One for each "zone". I don't play the in-boats very loud and adding the subwoofer really helped. Last year I went to a better sub (swapped some off branded thing for a Pioneer one) and swapped out the Infinity amp and went back with the 2 Kicker amps (the 250.2 was running the tower but I got the Exile 600.4 for the tower so I bridged the 250.2 and used it for the subw). The Infinity amp is on a shelf in the garage. It's just "available" but probably headed for the daughter's Mustang now.