What's the BUZZ between songs with iTunes and DAC


I am getting a really loud electronic crackle and buzz coming through my Airport Express when there is no signal (music playing), such as between songs and/or if I pause the playback in itunes. What's the buzz about?

I know I read about this in a discussion here but for the life of me, I cannot find it now. (Maybe it was deleted like so many threads that disappear these days)

Here's my set-up:
iTunes to Airport Express to Monarchy DIP (via optical) to digital in jack in CDP Opus 21 (via digital coax).

Also, sometimes when I begin play, the sound is degraded to an am-radio quality signal but if I pause and restart it comes back to high quality.

Any thoughts or help would be appreciated.
mcmanus
I need the Monarchy to convert the optical signal from the Express into a digital coax electronic signal for the input on the Opus. Otherwise I would not even have the Monarchy.
If you remove the Monarchy and run the Airport Express directly into the Opus doe the buzz and crackle persist? It sounds like your D/A is losing signal lock.