HDMI audio output not working

[Akito]

HDMI is not displayed in the "Sound" settings on Ubuntu 14.04 LTS

Fix no audio through HDMI when connected to TV in elementary OS

HDMI doesnt show up as playback optional

How to Setup HDMI Digital Playback in Linux - Make Tech Easier

https://forums.linuxmint.com/viewtopic.php?t=250454

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