How does a DAC defeat the purpose of having a computer? The carputer is not meant to be a cheap project. If your purpose in building a carputer is to save money on audio components....ur gonna have a crappy carputer.
I wouldn't know what you were trying to say without having read the cliff notes, but I have a Alpine PXA-H701 and that has time alignment, 4 way crossover, PEQ, GEQ, media xpander (for mp3's), bass comp, dolby digital, prologic II, phantom center channel, and the list goes on. It supports optical in (so all my sound is digital) and gives me a volume nob to use with my computer.
So...in summary. I am running a 3 way active crossover with a carputer and am getting digital sound.
Try searching for "Alpine H701" or "pxa-h701"