FCC filings submitted by Sonos in March suggest that the company is working on a new speaker, potentially a follow-up to the Playbar. The filings, which were first spotted by Variety, reference model number S14. The device will reportedly incorporate an HDMI port, which would be new for the Playbar. (It previously relied on an optical in port.) The label filing, which you can see below, depicts a microphone. This probably means the mysterious speaker will ship with support for Amazon’s Alexa voice assistant, just like the Sonos One from last year.
This is the label filing; it looks similar to the Sonos One’s device interface: