Wow looks like a lot of work and headache to get the ability to play a radio/cd player. I researched this a while back and elected to leave the stock head unit alone and completely go around the entire stock system. The key is to go completely digital. Leave your stock system alone so you keep your Nav, blue tooth and phone controls in tact. Using a phone you can stream or play your music files by sending them to a DSP that accepts a digital input. You will need to convert from USB to Tos or Coax but this means you don't have to go through the pain of rewiring your head unit, think about the benefit, what are you interested in? If it is to play SQ music then 2021 is way ahead of 2000. Why go back to that old tech. Before DSP developed the way they are now we needed a head unit to get signal split where we wanted it, now we have 8 to 11 channels DSP's where you can control everything there so no need for a head unit
