Hello I'm installing a Kenwood ddx396, and the stereo I had before this one was also aftermarket. Issue I'm seeing/hearing is everything sounds amazing in aux mode but it's complete opposite when I turn the car on. Any ideas of where I need to spot check.
By different sizes cables are you referring to the power abs ground cables? I have cheap-o used battery cable that I wired my amp up with with no problems. Is it possible the cable you were using had high resistance?