The ornamental design for a portablespeaker with suctioncup, as shown and described.
FIG. 1 is a perspective view of a portable speaker with suction cup, showing my new design;
FIG. 2 is a top plan view thereof;
FIG. 3 is a bottom plan view thereof;
FIG. 4 is a front view thereof; and,
FIG. 5 is a back view thereof.
The left side view and right side view of the portable speaker with suction cup are identical to the front view of the portable speaker with suction cup in FIG. 4.
The broken line portions are included to show unclaimed subject matter only and form no part of the claimed design.