TLDR - Arcana is an awesome device that fixed a major sound issue, as well as Atmos TrueHD.
My previous setup - Nvidia Shield TV → Samsung Q9FN TV standard HDMI input. Sonos Arc to Q9FN HDMI ARC port.
I had been having continual issues with no sound playing when I switched apps on the Shield. I had to force quit and restart the app to get sound again.
My current setup: Nvidia Shield TV → Arcana input. eARC from Arcana to Sonos Arc, HDMI from Arcana to Q9FN.
Arcana setup consisted of connecting the cables and power cycling devices a couple of times. TrueHD Atmos from Kodi works fine, as well as DD+ Atmos from the streaming apps. My Shield remote continues to control both the TV and the Sonos Arc, no reconfiguration needed.
After 2 days, the sound problem never appeared once. Under the hood, the whole HDMI / CEC / HDCP / eARC world is a huge Charlie Foxtrot. It’s a wonder any of it works reliably :)
I believe that the HDFury folks know more about that world than any other major company. Kudos to them for an awesome product !!!!