One issue you may run into is that the processing for 4K video likely takes somewhat longer than older video formats so setting the BDP lip sync for 4k may be different for 1080P. This may be why an on the fly adjustment is included so you can vary it for each source and maybe even the video format. Of course the processing speed of the BDP may be enough to overcome the sync issue altogether but who knows. It may also disappear depending on what you are watching. Outlaw Ben can chime in as to whether it is a universal delay or goes back to zero when you changes sources.