Yesterday I discovered that my Coax input is bypassed.
The volume control does not work anymore and it is not necessary to choose the coax input to listen to it. It is alway on!
I have already powercycled my DS with a few minutes down time. I have not loaded another firmware yet.

Are you saying that after powering off the DS and powering it back on the input still can’t be changed to something other than coax?
Have you tried doing it from the touchscreen instead of with the remote?
No it can be changed.
Now I’m using the coax while I selected the I2S input. The I2S for example works fine, but the coax works while any input is chosen. Mute doesn’t kill the signal (sound) that is fed to the coax input either.
It seems that the volume works on coax to a certain level while the coax input is chosen. When another input is chosen the signal of the coax will come through and the volume or mute can’t be used on it
I’m completely confused. I think I understand what you are saying, but it doesn’t make any sense if the DS is the only thing involved.
The mute is a hardware relay that shorts the outputs so it can’t affect one input signal separately from another.
Not that it exactly explains your symptoms but is there any chance that you have the coax plugged into one of the analog outputs or something like that?
I checked the coax on both side’s it was connected the way it should. But with mentioning the analog you set me on the right track. I have a headphone amp that has input A connected to the Blu-ray analog output. This is the same player which I use with the coax to the DS. The RCA analog output of the DS is connected to input B of the headphone amp. And there is the problem these inputs has double relais and have several functions one of them is to loop the signal from input A to B where B became an output on the Headphone amp.
So the analog signal from the Blu-Ray was actualy going in the analog output on the DS and going out the XLR of the DS to my poweramp. So my movie was a direct analog signal from my blu-ray player for a certain level 80 or 90% when setting the DS to 100 while the coax input was chosen the DS added some extra volume.
In any case the problem is solved.
Thanks for setting me in the right direction.
The manufacturer of the headphone amp made me aware. The basic setting for the relais could be changed with a jumper. In it’s standard settings the relais are in Pass through setup when the headphone amp is switched off. With a jumper change the relais will be in double input setup when the amp is switched off.