Abstract: An audio mixing console used in a recording studio etc. includes operators which can be driven both manually and by a motor, function selection switches for selecting one of a fader function and other functions in respective channels as a function to be designated by each of the operators, a display for displaying contents of separation assigned to the operators in accordance with selection by the function selection switches, a memory for storing operation positions of the operators for each of the functions, a control unit for reading out operation position information stored in the memory with respect to the function selected by the function selection switches and positioning the operators to the position by motor driving, and a signal processing circuit for applying to an input signal a signal processing corresponding to the position of the operators with respect to the function selected by the function selection switches.