Need Urgent Amp Install Assistance!

[ALE53]

Hey everybody I have my amp all wired up and ready to go, and am about to tap into the 2 sets of twisted pairs running to the NON DSP radio module/amp. I will be running my amp MONO to a single Infinity Kappa Perfect 10" in a custom box (in need of grey BMW carpet by the way...).

My PPI amp has RCA inputs, and I'm not confident that they just connect to the twisted pairs from the X5. I clipped the ends off a set of RCA cables and stripped them in preparation for tapping the wires from the X5 and hook up to the amp's RCA inputs......

My question is this: do I now need to split apart the two internal wires of each side of the RCA cable and connect them +/- to the pairs from the car? I don't want to be out of phase or F anything up! PPI's website does not instruct you to do this when adding RCA input cables from the headunit wires.