so this headunit only got 2 pre amp outputs (front, and Rear/SUB) so how do i hook it up get a one of those RCA Y plugs and hook the rear to both Rear of the bose amp and sub amp or just use the pre amp outputs to the bose amp and use a line convert with the speaker wires to use with sub woofer amp
thanks

The front should have a left and a right, and the rear/sub should also have a left and a right.

Your post makes absolutely no sense. If you have a HU that has 4v+ outputs get a metra 70-7551, if not get the schosche adaptor.

I meant the headunit only have 2 Preamp out puts (Front, and Rear/subwoofer) and i need the front and the rear for the Bose amp, so where do i hook it up ??

You should use the front and rear to the harness, then use a LOC on the outputs to the sub amp.