I'm planing on making a video for YouTube on how to do this.
But anyways, here's my current setup.
If your looking at the back of the oem head unit, remove the two connectors on the left and plug them into the larger connectors shown in the picture. Then plug the smaller ends, also shown in the picture, into the head unit.
Splice the ground, memory and power wires together, respectively. You can use the blue or blue with white stripe to power on your amps or splice them as shown.
Splice on the RCA plugs to the speaker output wires leaving the head unit. Front and rear, left and right.
Now you have 4 channels that you can amplify.
Make sure any amps you buy can handle high level input or speaker level input. I use Kicker amps which have this built in.
Run your RCA's to your amp/s.
Run your speaker wiring from your amp/s back to the wiring harness and connect to the wires that go to your speakers.
In the picture I have butt splice connectors with nothing attached, where you would be making these connections.
I had line output converters on my first go around. They sucked, so this is what I came up with.
I have had ZERO issues with this setup. The sound is crisp and clear.
I know someone on here will insist on using LOC's but I found them unnecessary.
Anyways, I hope this helps a little. Give me a couple days and I'll make a video where I can explain it better.
My goal was to NOT cut any factory wiring. Making the T harness gave me a place to splice into, however I want.
My next step will be full head unit replacement, and adding the Mastro RR for vehicle control settings.
I'll definitely make a video while I'm doing this.