Since the internal wake-up signals and FM radio do not permit adjustment of the wake-up signal volume, it may be desirable to use an alternative signal source. Connect a smartphone with Bluetooth, and set the Horizon to use the Bluetooth input for wake-up sound. If you reduce the output volume on your smartphone to a suitable level, you will experience a much lower signal volume when Horizon activates the smartphone through Bluetooth when the wake-up time has been reached. With a smartphone, both music from the phone's internal memory, its FM radio, web radio or streamed music may be used. If you want to wake up to a certain song, select the desired tune on the phone, and when it receives the Play command from Horizon, it will begin the right tune.