Hi @Giof, thank you for reaching out to the Sonos community. I appreciate you for sharing your concern with us. Let me help you with this.
Upon checking the specifications of your Samsung Q90T TV it has 4 HDMI connections, HDMI 2.1, and an eARC port. To receive a Dolby digital Plus encoded Atmos signal to your Sonos Arc, your Samsung TV needs to have eARC, and/ or that the TV needs to support transcoding LPCM signal. Other TV streaming devices can output Dolby Digital Plus (Atmos) may work through an existing HDMI ARC connection, but it is highly system and link dependent.
We can wait for suggestions and feedback from our Sonos community members, they might provide their own opinion about this. You may also contact our Sales specialist to know more about it. If you need help with any other information, please be sure to let us know. The Sonos Community is always here to help.
Did you end up unboxing the Q90T and if so, how does it work with the Arc when it comes to Atmos?
I bought the Arc with the Gen 3 subwoofer and I'm also planning to buy a new TV. Have been thinking about the Samsung Q95T but after reading some of the threads in here, I'm now a bit hesitant.
In another thread, it was suggested the one connect box which comes with the Q95 being the culprit. Where the Q90 without the one connect box doesn't have any Atmos issues. According to the last post in that thread though, it sounded like the Q95 now works too.
A bit confusing with all these threads to know what the actual and current situation is in regards to these compatibility issues.