RME ADI-2 Pro

I have tried RME ADI-2 Pro with Volumio installed on RaspberryPi 2. Installation was easy and I do recieve good quality audio output but also there are clicks/jitterinng I would say every 5-10 seconds. I have tested multiple formats and both wired and wireless connection. RME DAC is perfect and works flawlessly with both Windows PC and Android phone connected over OTG cable.

How can I debug what the issue is?