I can get the HomePod to work with the Symfonisk speakers simultaneously while eARC is enabled, but only with the Apple TV itself and not the other inputs on the TV (eg. cable box, PlayStation).
The issue is when I use the Apple TV with eARC enabled to play audio simultaneously using the HomePod and Symfonisk speakers and then switch to another input, all the other inputs only use the HomePod.
I had not realized that Apple TV had ARC/eARC capabilities as a sink for audio from your TV. Interesting. Regardless, according to Apple support, this function only works with Homepods, not any other airplay enabled speaker. What you’re seeing is expected. Not sure if this is a technical limitation, but I suspect that it is. Apple, like Sonos, would have a hard time syncing video on a TV with wireless audio, since wireless audio requires some buffering.
https://support.apple.com/en-us/HT207117
I was wondering if there’s a way to get the Symfonisk speakers to work with the other inputs using the Apple TV, eARC and the HomePod, and if not, if there’s another workaround that doesn’t involve a soundbar.
One workaround that seems possible would be to group the Symfonisk speakers with a Sonos Roam and pair those three speakers to the TV using Bluetooth, but it seems as if in the best-case scenario, that would likely only mean the choice between the HomePod through eARC or the Symfonisk speakers and the Roam as the TV doesn’t appear to have the option to play audio simultaneously using eARC and Bluetooth.
I don’t think that would have good results. As you mentioned, TVs usually don’t send audio through eARC and bluetooth at the same time. As well, the Symfonisk probably would be playing behind the homepod, creating an echo effect.