The ActivPanel is not designed to be a standalone amplifier.
The audio inputs on the ActivPanel are linked to the respective video inputs, so sound will be played provided there is a video input.
NB: For the ActivPanel Elements Series (firmware version 3.2 onwards) and the ActivPanel Titanium Pro, if there is a video input but no sound, please check that the ActivPanel speakers have not been disabled in the ActivPanel settings.
Open the Unified Menu and tap the Locker icon on the dock. Tap the Settings app*, then select Audio. Check the Panel Speakers option is not turned off.
(* If the Settings app is not visible, please contact your IT technician as they may have locked access.)
Should you wish to connect an audio-only device, Promethean recommends using a speaker system, such as the ActivSoundBar. Alternatively, you can route the sound through your computer by connecting the device to the audio in port.
Apple users might consider using Apple TV to connect audio-only devices.