For my Audio gurus...2016 mess

Hey Guys,
I just got this 2016 Limited Crewmax with Entune/Nav and the lovely previous owner (self moderated description) left me this...
I’m very electrically / Audio inclined so I can fix it... again Im just wondering if this looks like any plug and play setup you guys recognize?
It’s obviously been spliced and altered but, for what?
Just a DSP, amp or both? Any ideas, suggestions?
I saw the full harness from taco that runs from the HU but I don’t think that’s gonna work given this situation.
There are aftermarket component speakers that seem decent. I’m getting sound from all of them, less from the rear. I read on here the fronts are driven from the HU, please correct me if I’m wrong.
There are 2 holes drilled in the side of the console interior about 10” width. There is a volume knob mounted on the console rear of the shifter. I haven’t taken it apart yet.
The red wires appear to be speaker wires and not cutoff RCAS. The two wires on the right are a grey and white wrap, possibly multiple wires, didn’t look that close yet. There is no evidence of a sub anywhere.
Thank you in advance!

 

Good Luck with that. I have seen much worse.........

 

It looks like its the amp harness underneath the passenger seat.
There should be two harness - a small one for the power (12v+, ground, remote, and front speakers output) and larger one for inputs from the HU and rear speakers output.

Here's the wiring schematic of Non-JBL amp. I hope this helps.

 

Thank you Makoy, I ran across your post earlier and screenshot the diagram.
I’ll figure it out at some point, thanks!