Digital coaxial is an audio interface. Different from traditional analog audio signals, it is a digital audio signal. There are generally two types of interfaces: fiber optic or coaxial. Only one optical fiber or coaxial cable is needed to transmit digital audio signals. The input audio or power amplifier has a digital decoding function to decode the received digital audio signals. Digital audio has the characteristics of high resolution and good sound separation. It has been used by audio and video enthusiasts for a long time. However, with the advent of next-generation power amplifiers, optical fiber and coaxial digital audio have also been eliminated.