I haven't noticed a setup similar to mine mentioned here, so I thought I would pass this along.
I've had a UPnP/DLNA media server for a year or two. It looks like this.
It's a Raspberry Pi 2 running Arch Linux ARM. "Rygel" proved unsatisfactory as the server's UPnP software, so I settled on "minidlna" instead. Three 128 MB flash drives contain about 6500 FLAC files, plus several dozen movies and videos. The Ethernet cable is connected to a WiFi router a foot or two away.
Last month, I purchased a HifiBerry DAC Plus Pro, with the intention of creating a UPnP renderer. Here's the result.
This is another RPi2, in HifiBerry's steel case, once again running Arch Linux. "gmediarender" is the rendering software. Neither the server nor the renderer has a keyboard or monitor. I play music using a tablet or my cell 'phone as the UPnP control point. Music is streamed via WiFi directly from the server to the renderer. You can see the USB WiFi dongle protruding from the left end of the case.
By the way, this sounds excellent. Thank you, HifiBerry, for your DAC.