https://www.techradar.com/news/amazon-echo-sub-release-date-price-news-and-features

If you’ve been digging your Amazon Echo or Amazon Echo Plus speaker for all of its smarts, but find the audio to be lacking, Amazon has a new thing to sell you: the Amazon Echo Sub. This is a subwoofer attachment that enhances the audio of existing Echo and Echo Plus speakers.

Amazon just announced the Echo Sub during a surprise September 20 announcement event in its Seattle headquarters. The device works with existing Echo and Echo Plus speakers wirelessly for either a 1.1 improvement with a single speaker or with two speakers wirelessly, amplifying both of their audio and turning it into a 2.1 setup.