Duo X S/Pdif clock source

I want to send the audio from the Duo X to my Focusrite Scarlett 8i6 using the S/Pdif connector. This works, but occasionally i get some clicks in the sound, which I assume are due to clocking issues. In the controls for the Scarlett, i can set the clock source to S/Pdif, which prevents clicks, but when i turn the Duo X off, i also have no sound anymore.
has anyone dealt with similar problems, could this be fixed by somehow setting the clock source of the duo to external, or would this fuck up all of the audio clocking internally?

Kind Regards