Sometimes when we check the connected playback devices on our system, we see something named “Realtek Digital Output” on our system. But we always use some sorts of speakers or earphones as our playback devices. So what exactly is a Realtek digital output device? When we connect to any digital audio receiver devices like a home theatre digital output is used. Most of the times it comes in the shape of a S/PDIF optical port or RCA connector. Check the image below to know what exactly they are… It carries the digital audio signal which is decoded by the receiver and turned into the surround stereo sound.