It's true that genuine advances often seem trivial after the fact, and it can sometimes be hard to distinguish them. In this case, having one volume control mul

It's true that genuine advances often seem trivial after the fact, and it can sometimes be hard to distinguish them. In this case, having one volume control multiple connected speakers is how wired stereos have worked for many decades, so while it might have been state of the art in the 1930s, Sonos wasn't involved.