Today I have used the UR22 for the first time.
Before use I installed the driver on my Windows 10 computer.
I disabled the onboard audio in the UEFI.
Now I can listen to music with a USB headset.
The line output of the UR22 is connected to a my monitor speakers (via a mixer and a power amplifier).
The problem is that the mixer gets no audio signal from UR22 output.
However in windows at the speaker icon (the UR22 output is mentioned).
Why can’t I hear music via my monitor speakers so far?
You mention a USB headset? Those have their own integrated audio interface, so you will have to switch the output of your music program to whichever device you want to listen to.
Right click the windows volume icon and select show volume mixer. Here you can see which programs are outputting audio and to which output.
The problem is that the UR22 line output is shown in the Windows volume mixer.
However there is no audio signal received from the UR22 by my hardware mixer,amplifier and speakers.
So everything seems all right but I do not hear output.
So what could be the problem?
Did you turn the ‘MIX’ button all the way to input perhaps?
Yes I did.
Thanks very much for the solution Strophoid!
Excellent, glad it was easy 
Enjoy your UR22!