Where to splice

After talking with Crutchfield techs, I decided to focus on my front speakers to enhance the audio. I like the interface with the Entune head unit and don't want to replace it. I picked out the amp and front component speaker set. I will probably splice existing wires instead of rewiring through the doors.

My question is where us the best place to splice? My amp will be located under front passenger seat with easy access to battery. I noticed that the C's lower console disassembles easily enough. I did find the wiring schematics on the forum and I think this is fairly doable if I can tap into your expertise. Any help would be appreciated.