I've recently started to use the DAC+ Pro with Runeaudio on the Pi3 B and so far I'm impressed with the ease it all fits together and works which is ideal for my final intentions.
First testing was just using standard CD quality files to get up and running which is all good to test signal paths etc but now I'm starting to introduce other playback formats into the equation.
What I find is that if I create a play queue with varying sample rate formats then I get an obtrusive pop at consider amplitude when the queue transitions from one format to another. This only ever occurs at the star of the track - after the pop the audio playback seems fine and stable. In my case it seems to manifest when transitioning from standard CD Quality format to 192kHz - transitioning the opposite way doesn't seem to pop (although I will retest this).
Could this be a result of the clocks being switched?
I know that there are two individual clocks on board the DAC+ Pro, and these switch depending on the sample rate of the chosen material being played.
All hardware was acquired recently (v.late 2017 / early 2018) and also the Rune audio image too. (v0.3-beta I believe - currently auto-detecting the DAC+ Pro rather than manual i2c activation)
I will post more technical Pi OS data later today if required but would like to get to the bottom of the pop.
Any ideas gladly welcomed - 8)