In my case with Ubuntu 18.04.2, In order to reestablish the sound after have removed the HDMI cable I need: to reattach the HDMI cable and turn the TV on. Only then I can change the selected sound board to Built-in Audio again and only after that I can detach the HDMI cable.
In my case with Ubuntu 18.04.2, In order to reestablish the sound after have removed the HDMI cable I need: to reattach the HDMI cable and turn the TV on. Only then I can change the selected sound board to Built-in Audio again and only after that I can detach the HDMI cable.