My wires were a bit cluttered since I haven't cleaned everything up from the Joycon "install" (if you could even call it that); so I ended up making a diagram that should break it down.
So basically, coming out of the Metra harness it goes as such:
1. Metra > JTRON power adapter
2. JTRON > USB extension (needed a male/male)
* Only one of the JTRON outlets are used
3. USB extension > [Male input] USB to Male/Female Micro USB splitter
a) Female is used for wall power input
b) Male is used for vehicle power [Acc/On]
4. Male Micro USB to Lava OTG hub (#TL-002)
a) Power < Micro USB [Male]
b) Tablet > Galaxy Tab A (I used 5-pin OTG cables from the tablet to the Lava hub)
c) USB > DAC > 3.5mm to RCA cable > Crossover
Input (under driver's side knee pad)
Powered from wall with vehicle off
