Initial audio silence (delay) on Apple TV 4K Revisited

I finally updated our Apple TV to Apple TV 4K. However, I found that several video streams all suffered from initial silence. After anywhere from say 1/2 second to 2 full seconds, only video would play with no audio. Then, audio would begin. The audio was in-sync, so no issues there outside the silence. This was definitely not desirable, especially when picking up things where you left off.

Something about this was familiar though. On some Blu-ray movies, when switching the audio to the highest quality format (e.g. Dolby True HD vs default Dolby Digital), this also led to some initial silence. This leads me to believe this is not unique to the Apple TV 4K.

Having said that, I was able to fix the issue on the Apple TV by going into the audio settings and turning off auto. When doing this, you can select Dolby Digital 5.1. Now, audio will play back immediately along with the video when resuming playback.

Note: In an older thread last year (too old to append to; hence this new thread), it was mentioned that another possible fix is to set "reduce loud sounds" to OFF. However, we cannot do that since there is far too much differences between content we access.

Details of my setup:

• Central AV receiver; main HDMI out to a TV.
• 7.1 speaker setup
• Sources include the Apple TV 4K, Blu-ray, Cable box and varioius Wii systems.

The above issue was mostly happening with the Apple TV 4K and rarely with Blu-ray content.

Possible issues (though don't have enough research yet):

• These are bugs in the source equipment (streaming the audio is taking some initial performance hit. Since the delays were consistent with the same exact content, but varied amongst different content, this seems to be tied to the "complexity" of the audio. More complexity leads to higher delay.
• Or, the audio signal in the source equipment is immediately there, but potentially then a bug in the receiver where it is leading to this initial delay. I have no equipment to troubleshoot this in order to find out which equipment is at fault.