Hi, I have the same issue with my Samsung Q80T and 5.1 amp. There is a distinct delay when swapping the Xbox Series X from Stereo to Dolby Digital. You can see and hear this when using Xbox menu. In Stereo the navigation and sound are in sync but in DD the navigation box moves then the sound plays with a delay. This issue Microsoft need to resolve.
Using DTS doesn't work at all. If I select DTS then the Xbox just changes it back to DD. This may be because the Xbox thinks the TV doesn't support DTS.
I think Microsoft need to work with Samsung to investigate and resolve the issues as the delay gets even worse when trying to pass the DD signal through the Q80T TV.
When testing DD through the TV speakers there is a small delay that Microsoft need to resolve. If I then set the TV to Optical output and send the audio to my amp then the delay is even worse. The Q80T doesn't allow you to use audio pass-through for an Optical connection so you have to set the TV audio to Auto. It looks like the TV is then processing the audio rather than just passing it straight through which causes even more delay.
Samsung and Microsoft need to work together on resolving these annoying audio issues. As Microsoft have decided not to put a SPDIF output on the Xbox the TV should just be passing any audio signal through to the Optical output without trying to process the signal. Both DD and DTS signals should be supported without any delay issues.
