The ornamental design for a protectivecover for an audio listening system, as shown and described.
FIG. 1 is a top perspective view of a protective cover for an audio listening system showing my new design;
FIG. 2 is a front view thereof;
FIG. 3 is a rear view thereof;
FIG. 4 is a top view thereof; and,
FIG. 5 is a bottom view thereof.
The dashed broken lines in the figures show portions of the protective cover for an audio listening system or environment that form no part of the claimed design. The dot-dash broken lines in the figures show boundaries that form no part of the claimed design.