You can adjust the Volume Level for each of the onboard pads, or external pads in the SPD-30. Here's how:
1. Choose a Kit to Edit.
2. Press MENU.
3. Press the function 3 (ENTER) button for INST.
4. Press the function 2 button to select the EDIT tab.
5. Turn the Function 1 knob to highlight "Volume."
6. Hit the pad - or external pad - that you want to adjust the volume for.
7. Turn the function 3 knob to adjust the level (0-100).
8. Repeat Steps 6 and 7 for any other pads as desired.
9. Press the BACK button when you're finished. The new settings are saved in the Kit automatically.