The short answer is HDMI. The long answer is that there's two ways to get Atmos into one of these speakers -- the first, and best, is to have a TV with an eARC port (HDMI 2.1). This port is a feature of many new TVs and enables Atmos information to be fed from your TV (via either smart apps or another connected device) to an external speaker. Normal HDMI ARC will work for some streaming services that offer Dolby Atmos.  On the other hand, if you have an older TV and an Atmos source such as a Blu-ray player, you'll need a soundbar that has more than one HDMI port. The Vizio M512a enables you to connect external devices directly by HDMI.