The ornamental design for an audio mixing console, as shown and described.
FIG. 1 is a perspective view of an audio mixing console showing our new design;
FIG. 2 is a top plan view thereof;
FIG. 3 is a rear elevational view thereof;
FIG. 4 is a front elevational view thereof;
FIG. 5 is a side elevational view of one side thereof; and,
FIG. 6 is an opposite side elevation view thereof.
The broken lines shown in the drawings represent unclaimed environment only and form no part of the claimed design. The break that separates the two parts of the audio mixing console shown within the brackets and the portion within the brackets represents indeterminate length and forms no part of the claimed design.