The ornamental design for a biofeedback apparatus with a medical low-frequency generator, as shown and described.
FIG. 1 is a perspective view of a biofeedback apparatus with a medical low-frequency generator 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 line portions of the biofeedback apparatus with the medical low-frequency generator in FIGS. 1-7 represent unclaimed portions of the claimed design and form no part thereof.