Use the DAC on a receiver

Now that even SOHO routers have a USB host port, you could probably just run an audio server on a $100 router with a $50 USB digital audio adapter and have as good a sound as is possible with your receiver's built-in DAC.

I've been running the same little USB to TOSlink adapter for about ten years, feeding input to various receivers I've used along the way. In my case, MythTV supports pass-through Dolby Digital and DTS surround from HDTV recordings or DVDs, which is likewise decoded by the DAC on the home theater.