That is what they call multi modeing!!!!!! Do not attempt to do this unless you know what you are doing!!!!!! Or it will fry your amp. you have to fit capacitors to all othe speakers running in the car and a l/p coil to any subwoofers bridged on those channels. I know because I'm a car audio fitter!!!!! Kids don't try this at home!!!!
P.s :- ALPINE RULES!!!!!