The ornamental design for a portableaudiodevice, as shown and described.
FIG. 1 is a front perspective view of a portable audio device showing our new design;
FIG. 2 is a front view thereof;
FIG. 3 is a rear view thereof;
FIG. 4 is a left-side view thereof;
FIG. 5 is a right-side view thereof;
FIG. 6 is a top view thereof; and,
FIG. 7 is a bottom view thereof.
The broken dash dot lines indicate the boundary of the claimed design and form no part of the claimed design. Other broken lines indicate unclaimed portions and form no part of the claimed design.