The ornamental design for a powersupplybar for mobile audio systems, as shown and described.
FIG. 1 is a perspective view of a power supply bar for mobile audio systems;
FIG. 2 is a front elevational view thereof;
FIG. 3 is a rear elevational view thereof;
FIG. 4 is a top plan view thereof;
FIG. 5 is a bottom plan view thereof;
FIG. 6 is a left side elevational view thereof; and,
FIG. 7 is a right side elevational view thereof.
The three linearly-arranged cone frustums shown in dashed lines on the top of the power supply bar illustrate set-screw-type fastening devices that can be used to hold a conductive wire within the power supply bar and form no part of the claimed design.