The options before were for over HDMI
Always convert (to Dolby 5.1)
Follow content
Disable (same as PCM 2.0)
So the key change is that you get PCM 5.1 instead Dolby 5.1. The other two are the same and Follow Content will output either Dolby 2.0, 5.1 or Atmos depending what's in the content.
I believe that PCM (either 2.0 or 5.1) can resolve audio sync issues with some setups.
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I work for Virgin Media - but all opinions posted here are my own