[Origins]

Hello,
I have installed Kodi 20 on Windows 10 64bit on my Beebox-S U7100 with 8GB RAM, 500 GB SSD, the installation process went smooth.

But I am having issues with the HD audios when playing a video. I have my Samsung 8K TV connect it to Yamaha receiver HDMI (eARC) output and my Beebox to Yamaha RX-A1080 receiver HDMI input.
I have passthrough enable on Kodi 20. When I play a 4K video are every few second audio dropous/glitches or no audio at all.
AVR also shows "Decoder off" and speaker icons disappear for 1 second.
!f the Beebox-S was disconnected from the mains, will playing a movie without audio, then Beebox-S Kodi 20 must be restarted twice.
Log file

[PatK]

I digress, perhaps this post might be served better in the hardware section (I'm unfamiliar with the capabilities of a BeeBox-S). From what I can see, it looks like you've connected TV>AVR (through eARC), the bottle neck might be the TV trying to decode audio (passthrough just moves the signal to the TV to do the decoding effort). I suspect the present set-up might work using Kodi directsound to do the decoding. What does your set-up look like when connected Beebox-S HDMI output wasapi passthrough>AVR input>AVR output to TV HDMI input using the AVR connected to speakers?

[Origins]

@PatK 
This is exactly my setup is: Beebox-S HDMI output connected wasapi passthrough>AVR input>AVR output to TV HDMI input and connected to speakers via AVR.

[PatK]

The first post indicated eARC which would mean the signal gets filtered through the TV first. If settings in Kodi will not resolve this (note the two locations in audio to be set, along with the AVR decoding capabilities), then I would look a bit more seriously at the Beebox-S hardware. Use the built in Kodi diagnotics for debugging Keyboard controls (wiki) perhaps you will see limitations in fetch and frame drop.