In the configuration section of the Wiki, there is a wonderful 4K/HDR section on video configuration. It has great detail, very helpful instructions on how to configure the settings in various circumstances, and useful, clear explanations about why. It's some of the best Kodi-related wiki information I've seen.
I can't find any information on audio configuration though, except Pulseaudio. There are a lot of audio settings and I'm basically guessing with little understanding of what I'm doing.