Hi, I'm running Debian 9.4, and the sound from the headphone port works fine. However, when I use the "Sound" configuration app to switch to "Digital output (S/PDIF)" and connect the optical out to a DAC, I get no sound. I also tried using a receiver instead of the DAC, but still no sound.
I hope it might be close to working, because under "Device settings" it says "Digital Stereo (IEC958) Output" in the drop-down.
Is this a supported configuration? Is there some kind of setup I'm missing?
Quick follow-up: I noticed that when I switch to S/PDIF, the port lights up in back, but when I switch to a different output, the light goes out. This seems to be more evidence that it's at least trying.