I've just replaced my F8000 with a Q9FN. I use Sky Q and any Dolby Digital (DD) signal (HDMI or optical) to the Q9FN results in an audio delay issue that I am unable to correct within the menu of either the Sky box or the TV.
The issue is that DD audio already has an audio delay, even with 0ms of delay on both the Sky box and TV - but the audio delay correction setting is only positive, not negative. The audio is correctly identified by the Q9FN as DD.
Setting the Sky Q output to 'Normal' gives correctly synced video/audio through the Q9FN.
Passing Sky Q Normal or DD direct to my Sonos Beam gives correctly sync'd video/audio. Leaving this in place is not an option for me as I connect other devices to the Q9FN and rely on their audio being passed to the Sonos from the TV.
Suggestions gratefully received from now till mid-Feb 2019 when the 100 day return window closes.