USB Audio support

[Darth.Severus]

I just found out that even if you get your Hifiberry card running then you don't have Dolby Surround. It doesn't pass through the DD or DTS signals, and with Pro Logic I got only Sound from the front speaker. So, I wasted many hours just to find out that Raspi can't be used as a HTPC with an old TV. I'm going to use it until I got some better computer which can be used as HTPC (better Television will take time).

I think external cards only make sense if you want to use them for music with better sound. Otherwise maybe a hdmi to 5.1. audio extractor may help, like deleyCON HDMI Audio Extractor.