I have bought an aftermarket off-brand 7" screen for GPS/DVD/Radio/etc.
I bought a harness adapter from Scosche and this is it:
SO my problem is that the
sound quality is so weak!
I've connected all the wires that were on this harness to the player..
Then I noticed that there are actually 3 harnesses in the car. I believe the third one is the steering wheel controls but does it also include a "stock amp wire" by any chance?? There is definitely bass missing in my sound.

That third one boxed out.
close-up
What are each of these wires for? Where can I find out? Any help at all would be appreciated.
Thanks in advance guys.