The issue

After connecting my speakers to the Realtek optical sound output on my motherboard, I got not sound when adjusting the output to 24-bit 192000 Hz in my Windows 11 settings.

The solution

Having tried a lot of various things that did not work out, I randomly turned the Spatial sound option in Windows to "Windows Sonic for headphones". This somehow activated the optical output. Afterwards I could deactivate it again and "keep the sound".