50W Audio Amplifier
I'm considering grabbing one of these devices for the audio amplifier.
It's easily found on EBay, Amazon, and google searches as:
"TDA7850 50W 4 CH 12V Car Audio Amplifier Board DIY Kit"
However it's a fixed gain amp, so on the plus side everything is controlled by the computer.
The down side is that every bit of noise will be amplified too.
Let's hope it's not too horrible when it arrives.