Why don't you tell us why it is tricky?

So? Google figured it out. The parents doesn't explain the tricky way to do it.

Maybe it is tricky, considering that Sonos can’t even get the volume adjustment of a single speaker to work, but unless they used specific technology/code developed by Sonos, how is affecting several volume controls/levels simultaneously at relative rates using rather basic math patentable to you?

Sure, maybe the rotten patent system allows it and the rotten court system validates the corruption, but that won’t change if people keep just referring to the corrupt methods implored. And I’m no fan of these corporations that are way too big and way too despotic.