There are a few things you can try to fix the issue. The DAC+ will work great anyways. In your current setup, however, with the HDMI output, the Pi should be the issue. Please check if you have Kodi on or on autostart, test it with just Jivelite and Squeezelite running. Also, please try connecting the Pi to another device like a TV via HDMI to rule out the port as the origin of error.
If you have another Raspberry, please try it with the image you are using on the one with drop-outs.