Factory Sub Wiring to Aftermarket HU
 

Looking to pick the the brains of some audio experts. I have the factory sub hooked up to my DDX919WS though the T harness that comes with it. The T harness splits the front speaker signal and sends one set of wires to the factory sub harness in the trunk, and the other set to the factory amp.

My questions are is there any benefit to figuring out a way to wire the sub into the head units RCA outputs as opposed to running the sub off the front speaker signal. My main concern and motivation is being able to adjust the crossovers and tune the DSP of the HU, and adjusting anything for the front speakers will also adjust any signal going to the sub. While I don't know if that's bad or not since I'm not an expert I feel like its less than ideal.

Secondly if there is a benefit what are the best options to go about accomplishing it without cutting wires. I have the factory bass limiter for it that I can add wires to, and two leftover L/R channel female RCA connectors from my KTP-445U would running a set of RCA cables from the head unit to the back then splicing them into the limiter be a good idea?

Here is the only alright picture I could find of the T harness.

https://imgur.com/eNiGqaT.png

And the limiter (which just removes 1 channel from the harness.)

https://imgur.com/nyvcevx.png

is the sub taking a high level or low level input?

That's a good question. So the sub T harness has 2 sets of orange/black and grey/black wires. One set goes through to the factory harness the other set goes through to the Sub. Then 2 come back from the sub that are just orange and grey that go to the factory harness.

honestly, i think you're better off abandoning the oem setup once you update the deck.

it doesn't look like it would be all that hard to put a different aftermarket amp with that enclosure...