Pad Chase is a feature in the SPD-S that shows which pad is being hit (selected) while you're editing parameters. If Pad Chase is off while you're editing parameters for a pad, you will need to select the pad(s) manually - (Hold SHIFT and press < or > ).
This feature (when on) will also display/select the SPD-S's pads if sending MIDI notes to the SPD-S from an external device.
Here's how to turn Pad Chase on or off in the SPD-S:
1. Press SETUP.
2. Press ENTER (SYSTEM).
3. Press PAGE right to choose "Pad Chase."
4. Press (+/- ) to select ON or OFF as desired.
5. Press EXIT when you're finished. The new settings are saved automatically.