I've been working on the hardware part lately since the software part is quite mature now.
I've fitted a cheap USB board with 2 relays to drive the amplifier. Now, the amplifier is only powered once the carputer has booted, and is shut off first thing when the carputer is shutting down. This avoids getting some interferences during the boot when the USB sound card is not ready.
I've also started to replace some parts that were manually crafter by some 3D printed parts. This is still a work in progress as I need to fine-tune the parts design.
First part I printed is a replacement for the box holding all the electronics where the factory radio was sitting. It fits nicely in the car, I now need to design the other parts like the screen frame to make sure that they integrate nicely all together. I have also printed a 1:1 replica of the LCD panel and its PCB to avoid the need of using the real display for prototyping.
The parts are available in Github.
The current, aluminium-based prototype :
The new part being printed using PLA: