A digital mixing system has a console having a display and an operator for transmitting and receiving a control signal, an engine having input channels and output channels for mixing a plurality of audio signals fed from the input channels while exchanging the control signal with the console and feeding the mixed audio signals to the output channels, and peripheral input and output units connected to the input and output channels of the engine, respectively. The console and the engine are located remotely from each other, and a cable connecting therebetween is duplicated for the purpose of fail safe. The engine may be installed in pair. If a main engine fails, a sub engine backs up instantly to continue the mixing operation. The console may be also prepared in pair for the purpose of fail safe.