That would be option #4 for a ZX3, but I have a wagon with four doors.
I know my options, I'm just curious to see what other's have done. That is an interesting thought though. If someone doesn't use the rear doors, they could tap into the rear door wires before they go to the rear door, and connect the f+r behind the HU. That means less wire ran.
For a high-end audiophile setup, that's too many connections for me. Plus I want heavier gauge wire. I'll probably run all new high quality 12ga. wire to the doors via drilling and grommets. One wire from amp to passive crossover.
DRZ9255 ~ Arc Audio 4150XXK ~ Oz Audio 180CS ~ IDQ12 ~ iPod ~ Sirius