[fragmede]

The $10 Lightning to 3.5mm dongle for my iPhone has a microcontroller with RAM and an ADC, and the $20 lightning to Ethernet adapter has an Ethernet phy in it, so it's just a matter of someone getting funding, building it, and selling such a product. Latency would be a concern, but get a good firmware engineer on it.

It should be noted that the wifi version of this is sold by Sonos though I don't think they do surround sound for movie watching, but are focused on multi-room audio.

[jfim]

Sonos does surround audio with their sound bars, and you can connect them with Ethernet. There's also a hack to take the IKEA Sonos bookshelf speakers and connect them to different speakers, eg https://makezine.com/article/maker-news/hacking-the-sonos-ik...