I was trying to get Raspberry Pi 2, Digi+ and Benchmark DAC to work with RuneAudio or Volumio. Both of the SW images had this strange problem where most of the time output was just white noise. When stopping and starting the playback multiple times, it occasionally started to play beautifully, but this happened very rarely. It seemed like the output volume is somehow randomly very much off the charts, as sometimes it also played very very quietly.
I then tried the test image, and it was outputting a very loud beep that sounded almost like square wave, not the sine wave I was expecting.
Benchmark DAC is working fine with other devices like Airport Express.
Digi+ Test image outputs squarewaveish sound