Since I've turned off the sync option in LAV it's been grand in every room today. Will keep testing.
You said earlier that you were using FFDshow audio decoder (which also was apparent from the logs) - is this not the case now?
The LAV 'Auto A/V Sync correction' setting is in LAV Audio Decoder - it has no effect if LAV Audio is not being used for playback - is this the setting you mean?