The Kicker zx300.1 is intended as a subwoofer amp. The xl350.4 is intended to drive 4 speakers. The 300.1 has input and output RCA jacks, so I think you could run the back two RCA ports on the stereo to the 300.1 then the output from the 300.1 to one half of the 350.4. The other half of the 350.4 would come direct from the stereo.