If anyone is based in/around Europe, can I also just throw-in this extractor/splitter device into the thread here aswell for consideration. This is an alternative to the Arcana Extractor & Splitter products …as this device from Feintech is a ‘combined’ solution that supports all the relevant codecs mentioned too:

VAX04101A

https://feintech.eu/en/products/feintech-vax04101-hdmi-earc-pass-switch-4x1

I’m not affiliated to the product, other than I purchased and use one myself. It works well and so just posted here as a further device to perhaps consider. 

@GuitarSuperstar , thank you so much for your detailed answer. It is everything I was looking for. I will try the arcana ( first with the Panasonic UB9004 ). If it works as everyone says, I will then buy a switch to connect everything else ( Xbox series X, PS5 ). I was actually going to buy the new LG 2021 just because I love the LG performance. Sony Bravia is expensive and the Panasonic has poor software, as far as I have been reading. 

If you don’t mind, because I’ve been checking videos of Arcana setup but all of them are for the Apple tv 4k, I have a last question. The Panasonic UB9004 has two HDMI outputs, one for audio only. Currently it is connected to the LG TV by the normal HDMI Output. Once I have the ARCANA, should I connect the HDMI audio to the Arcana, and the normal HDMI output to the TV ? Or just the normal HDMI output to the Arcana and that’s it ( like if it were an Apple TV )

Until today, I thought my LG OLED 2017 had eARC, because it does support Dolby Atmos. When in actuality all 2017 LG OLEDs support for 7.1/Atmos/DTS:X sound is packaged in DD+ (Dolby Digital Plus) and then sent to external audio device (AVR or soundbar) to be decoded. So, this is not true eARC, just a way to get more channels over standard HDMI ARC. So probably I will get a boost in audio performance once I have the ARCANA. 

Again, @GuitarSuperstar, many thanks for your answer, also everybody else. It is amazing how people like you all are helping us in the best possible way to get the best of our setups. 

Just use the normal HDMI OUT (video/audio) on the UB9004 and connect it to HDMI IN on the Arcana. This is how I have my Panasonic UB820 connected and it works great.
 

In order to get lossless Dolby Atmos, Dolby TrueHD, and multichannel PCM audio from Blu-ray discs to play out of the Arc, you MUST have a TV with HDMI eARC (or Arcana). So, yes, the Arcana will give you a significant boost in audio performance from all of your Blu-ray discs. Personally, I think lossless Dolby TrueHD/Dolby Atmos sounds much better than the lossy Dolby Digital Plus/Dolby Atmos you get from streaming apps. And I think you will hear a significant difference between lossless multichannel PCM compared to lossy DTS Digital Surround.

One more tip: Since you are getting the Arcana, HDFury recommends using HDMI cables from KabelDirekt, Cable Matters, or Zeskit. I use these cables from KabelDirekt with the Arcana and haven’t had any problems:
https://www.amazon.com/gp/product/B07CMF1VJZ/

But you should still use the Sonos-supplied HDMI cable that came with the Arc to connect it to the Arcana. The other cables are just to connect the TV and Blu-ray player to the Arcana.

I have a LG CX  with a panasonic ub820 4k player, and there was only one way i could get standard dts 5.1 surround from a older blu ray disc to work on my beam 2.

I did this using the optical out on the player, converted to hdmi (using the connector they supply) and going straight into the beam 2 and NOT the LG tv.

It means i have to pull out/swap the eArc cable from tv to beam 2, that is normally connected (which gives me atmos and dd hd), in order to get dts 5.1 surround from blu rays. But this is only on the occasion a fancy watching a older film from my collection.

I did it yesterday with valkyrie 2008.

Its a shame sonos dosen’t support DTS-HD though, i hope they do a update for it in the future.

Cheers m