After updating to the latest iteration of High Sierra (10.13.6) on my MacPro (cheesegrater) this afternoon, I cannot load my Sound Preference panel nor get any sound to display.
What if you disconnect the optical audio, does that make a difference? I guess the connection to the LED Cinema Display’s speakers is via the mini DisplayPort cable so you can’t disconnect those without also disconnecting the monitor.
If you run System Information, what does the Audio section display? My 2016 MacBook Pro has a Devices section and an Intel High Definition Audio section, the text can be copied and pasted from the application:
Devices:
Built-in Microphone:
Default Input Device: Yes
Input Channels: 2
Manufacturer: Apple Inc.
Current SampleRate: 44100
Transport: Built-in
Built-in Output:
Default Output Device: Yes
Manufacturer: Apple Inc.
Output Channels: 2
Current SampleRate: 44100
Transport: Built-in
DisplayPort:
Default System Output Device: Yes
Manufacturer: Apple Inc.
Output Channels: 2
Current SampleRate: 48000
Transport: DisplayPort
I did not think to look here, it would have been useful. Thank you for the suggestion.
I solved my own problem by removing a couple of audio related .kext files I no longer needed (Boom2Device, for instance), and by upgrading Audio Hijack. I’m guessing there was some conflict that shut down all audio.