Unless Im missing something here why 3 subs that dont match? and odd # subs always create ohm load problems unless you have a good amp that can handle the low ohm load why not just run 2 subs and each of them getting more power, a more stable ohm load, and turn the gain down. Again its not a volume knob like the others said. I highly suggest looking into learning how to "clamp" and amp thats the only correct way to run and amp.