**Unless you have an older Apple TV 4K and/or a TV that's not manufactured from the last 5 years or so, do NOT follow the instructions below.
With the newer 4K TVs and especially paired with the newer generation of AppleTV, leave the Dolby Vision ON and leave Frame Rate Matching OFF or you will have audio sync issues. Newer TVs are already smart enough to detect frame rate so no need to do any of the instructions below.**
The most prevalent issues as of this writing when using an Apple TV 4K with an A/V receiver:
- Everything is converterd to Dolby Vision when enabled.
- Laggy remote.
- Audio sync.
The obvious problem to this is that non-DV content look horrendous with this enabled. To get rid of this unfortunate default setting, you need to turn on dynamic range and frame rate matching. Not only does this get your non-4K fixed, it also used the proper HDR format that is encoded with the movie--i.e., use HDR10 (e.g. The Martian) when its the HDR format the movie is encoded with.
This is somewhat related to the first issue. When Apple TV detects that your display supports Dolby Vision or HDR, it will prompt you to use that format in everything, including the menu. This makes browsing so laggy. To avoid this, set the menu to 4K SDR; you still have the higher-resolution menus, but the lagginess and animation stuttering is gone.
I'll cut this one short: it's an Apple TV issue; it cannot deliver HDR/DV along with multi-channel audio without synchronization issues. The bad part is that sync gets worse over time which can only be resolved by rebooting Apple TV! So until Apple resolves this, the only way to avoid this is to set audio format to Stereo. Either that or adjust the audio sync on your A/V receiver every time a DV/HDR is watched, which could be different for every movie.