Welcome to the forum, If you are going to keep your stock stereo, than I would purchase a speaker level to low level (RCA) converter and run RCA's back to your amp. Plus if you run RCAs now, and decided to go with an aftermarket head unit. You'll already have the correct wires under the carpet and ...
I'm getting a p600x4 and was wondering if there's a big difference between the two I will be keeping my stock stereo
So should I get RF-HLC4 or RFIF2SW?