I have a Mac Mini and am getting the sound of it by plugging a TosLink (SPIDF) optical audio cable into the headphone socket. I set the sound to go to "Digital Out".
When I plug headphones into the socket, the volume controls are enabled, including the volume up/down keys on my wireless keyboard.
When I use the TosLink cable, the volume controls, and the volume up/down keys are disabled.
How is it possible to enable the volume controls while using the TosLink cable and Digital Out setting?