It appears the setting / kodi code that is relevant is actually “Send low volume noise”
Well ‘Keep audio device alive’ does ensure the audio device (HDMI/SPDIF) is always ready to send audio so there’s no possibility of delay or missed audio caused by the device on which Kodi is installed.
Then ‘Send low volume noise’ does the same for the far end audio device (HDMI/SPDIF) so it’s always ready to receive audio so there’s no possibility of delay or missed audio caused by the TV/AVR/whatever.
https://forum.kodi.tv/showthread.php?tid=311370&pid=2563342#pid2563342
