It’s turns of any device with HDMI-CEC support. Sure there isn’t a setting for that on the soundbar if it’s connected using HDMI? It’s probably enabled in the AppleTV Settings already, but check Settings - Remotes and Devices - Control TVs ans ReceiversIf only the power button on the remote could be programmed to turn my sound bar on/off via infrared, I’d have an excuse to upgrade my old HD Apple TV.