FIG. 1 is a top, front isometric view of a portable speaker system, showing my new design;
FIG. 2 is a top, rear isometric view thereof;
FIG. 3 is a front elevation view thereof;
FIG. 4 is a rear elevation view thereof;
FIG. 5 is a right side elevation view thereof;
FIG. 6 is a left side elevation view thereof;
FIG. 7 is a top plan view thereof; and,
FIG. 8 is a bottom plan view thereof.
All of the broken lines shown, including the two front circular speaker grills seen in FIGS. 1 and 3, are included for the purpose of illustrating portions of the portable speaker system that form no part of the claimed design.