Biz77 beat me to it regarding ATV. I use ATV2 in my home cinema set up and can confirm that i have no issues streaming DD (640kps) and DTS (1536kps) using XBMC via toslink to AV receiver. You also get the option in the future to fit headrest monitors and pass video via HDMI to the monitors with far superior quality than most current in car dvd players and at a fraction of the price thru a HDMI splitter. You will still retain all the AE connectivity you want.
With regards to noise issues(not read the links provides) but would a good quality ground loop isolator in the output from the DAC not help?
Just my tupence worth