Having suffered from lip sync issues with Sky on my new Samsung TV, going to my Sonos Playbar, (feeling I needed a negative audio delay setting) I finally found a solution.
I had wanted to go HDMI ARC to Sonos Playbar to see if it solved things but it only has an Optical input.
So I spent £20 on a "PROZOR HDMI ARC Audio Extractor 192Khz DAC Converter" from a well known online site. This allows you to connect HDMI ARC (or eARC) to the converter by HDMI, and then optical from the converter to the Sonos Playbar. So you're in effect connecting HDMI ARC to the optical-only soundbar.
Selecting 'Pass-through' in the TV's sound options for the HDMI ARC output meant that the TV didn't get involved in the sound before outputting to the soundbar, and immediately the lip sync issue was cured.
For info, HDMI Audio Output on the Sky Q box itself is set to Dolby Digital, and I still get 5.1 through my Sonos surrounds using this converter.
I hope this might help other soundbar (or even AV) owners who have lip sync issues and who only have an Optical input option.
Sky Q lip sync solution - Optical soundbars
