Finally I got my FIIO KA11 to stable route audio over the DAC (at least until reboot, including listening multiple folders of flac and mp3 files stored on the internal memory and switching to internet radio back and forth) .
I did follow more or less the steps described here:
Beware of typos in the text, e.g. section 3:
‘pactrl load-module module-udev-detect’ is incorrect
‘pactl load-module module-udev-detect’ without r is correct.