Yeah dude what a guy, I have a pixel XL same issue, installed my own amp and sub and wouldn't do half those things....
Same issue like the guy with the note 4, my note 4 worked perfectly but the static on the pixel comes in in-between vocals on songs. Driving me crazy.
I'm running an infinite mono amp, with that non-bluetooth JVC double deck that most people get. Tried multiple aux cables doesn't work, I'll try a splitter soon with headphones but it looks like maybe after market equipment might be the issue ? I just wanna listen to my tunes