I play files from a Foobar Library using BubbleUpNp Android (on a samsung tablet) selecting Volumio 1 on my Rpi 3 as the renderer. The Rpi 3 has the Hifiberry Digi+ board and I use the coaxial digital out to an external Dac.
MP3 files play great, FLAC rips from CDs play great too. However high res files such as for the PONO result in a terrible white noise.
To help diagnose, I hooked the Android tablet up to the DAC using USB, and selected Local Renderer in BubbleUp. The DAC plays the high res files this way no problem. So I conclude the problem resides in Volumio/Rpi 3, because the Foobar library played through the BubbleUp with the Android as renderer USB out to the DAC perfectly.
Please help as I much prefer to use Volumio RPI3 than a wired USB connector to my tablet and when it works, Volumio/RPI does sound great.