internal speakers don't show up as option in System Preferences/Sound
Internal speakers don't show up as a device option for sound output. In the list of options, the first is a line, next is AirPort Express, then Apple TV.
When I plug in headphones through a USB port, they don't appear as an option either.
I am using High Sierra, OS version 10.13.6, machine is from late 2015.
iMac Line (2012 and Later)