Dropout with my first Musical Fidelity DAC w Sonos

I am running a wired Sonos music system throughout my house.
The Sonos works great and sounds better than you would think.

I decided to add a Musical Fidelity V3 Dac to one of the Sonos digital outs to my Preamp in. Sounds good but I am experiencing momentary dropouts of sound.

The source is my PC based music server

I am using a Toslink optical cable. I hooked up the DAC and cables to a Sony CD Player and it works perfectly no issues.

My Spidey senses tell me that it is an issue with the PC.

But I am an Analog man at heart and have no technical understanding how to fix this.

Any suggestion would be appreciated, there has never been an issue that this forum has not resolved.

Thank You for your time!
If you have an option to use something other than the Toslink cable, do it. I found I had dropouts all the time with my good (Wireworld) toslink running from my Tivo to my Aragon processor. Just would not link up reliably, the Aragon was always flashing "signal lost." I now use a different Tivo with a coaxial out and no longer have the problem. If you are stuck with Toslink at least try to use the snuggest connector you can find.
Weiserb, have you researched this on the Sonos digital forum? I think someone else was having problems with a Musical Fidelity DAC, although I think it was the TriVista. Let us know what you find out.
I have Sonos connected to my dac also without issue. Like sc53 suggested, try using either the analog side or a different digital cable. Have you had issues with dropouts before?
I will try a coax cable, I never had any issues before.

The Sonos site does not address this situation.