You can play Tonics through an external sound system such as a hi-fi, depending on the device you are using. If you are using iOS, you can connect to an external device as usual via a cable, Bluetooth or AirPlay. When playing a Tonic, you will see an icon in the top right of the screen if external devices are available via Bluetooth or AirPlay (see screenshot). Please note that some of the ingredients only work properly with headphones. In particular binaurual beats, ASMR and other bilateral brainwave stimulation techniques require different sounds to be played in each ear, so listening with loudspeakers will not have the full effect, and listening via one loudspeaker or mono sound equipment will not yield optimum results.