> Spoiler, it contains a detailed description of the functionality, complete with UI mockups and flow charts. It does not contain any novel method for keeping audio in sync between rooms, for example.

Every software patent is like this, I've never seen anything relevant yet that I can't come up myself thinking about domain. They are very vague and useless on purpose.

Genelec 8250A active monitoring (speaker) systems were in production from 2006 to 2016. The Product Documentation (2006) has on page 7 screenshots showing the ability to define multiple groups of speakers and jointly control the volume level for groups via LAN. Extensive customization included individual time delays as well.

So back in 2006 Genelec was already doing all of this and had shipped products to the market.

https://www.genelec.com/previous-models/8250a

https://assets.ctfassets.net/4zjnzn055a4v/2Jy6loSGRWecUWacsq...

https://www.genelec.com/-/blog/glm-and-smart-active-monitori...