This is my version of installing a tablet into a car.
I went the route of running a preamp to amplifiers in my trunk to power all speakers
Wire harness explanation
• CAR TABLET wire harness explanation
Products used
Amazon Fire 7 tablet
SoundStorm S4EQ Preamp
Skar SKM4004D
Skar SKM5001D
2 12 inch American Pro subs
JBL gx600c door speakers
JBL gx962 rear deck speakers