I have two very old black box LEDs that have the typical two channels of blues and whites. There are no controls on these lights....each channel is either ON (100%) or OFF. I'm currently not using these, but would like to modify, if I can, by installing potentiometers so that I could adjust the level of light. Is this possible? And if so, what pot's do I buy, and where does it get installed (I'm guessing on the low voltage, DC side, if possible)? Typical with Black Boxes, no labels on any of the components:


