clock output

[plonkywonki]

With Lumin U1 Mini as source I use its clock as clock source in my digital system.
Now I notice this clock is always outputting except when the system is muted.
I try to understand, why is the clock signal gone when muted?

 

[wklie]

Which output?

 

[plonkywonki]

Which output?

I noticed it on the spdif optical and coaxial outputs