Like the Odyssey project, a clean mobile tablet installation has been on my list for ~10 years now. I started taking steps towards actually developing the project when I bought my 2003 Mercedes E55 AMG in 2016, which, like the BMW had an outdated audio system helplessly tied to the car's proprietary data busses. Unfortunately, I wasn't happy with the E55, so when I sold it at the end of 2016 and picked up my e39, my plans transitioned to the BMW. Another 6 years down the road and I'm still tossing around this project. I've decided to give myself a break and incorporate a Joying headunit vs trying to build from the ground up and piece together something completely custom. With that in mind, my goals are now revised to include:

• Remove the e39's stock headunit, and dsp / amplifier combination but leave all stock wiring unmodified so that going back to stock is a trivial operation.
  
• Replace the factory headunit with a 10.25" Joying Android 10 HU
  
• Assume the responsibilities of the vacant stock dsp / amplifier with discrete aftermarket amplifiers and dsp that can process an active 8 channel setup.
  
• Design a 3D printed bezel to house the joying headunit's LCD in the e39 dash while retaining a polished and factory feel.
  
• Retain steering wheel controls
  
• Add backup camera that cycles automatically when in reverse.
  
• Link head-unit and DSP with digital S/PDIF to transfer lossless 2ch LPCM.
  
• Assume control of the stock speakers via the aftermarket dsp and amplifier(s).