Originally Posted by Mike L
Only until you burn up the power supply. LED's operate within a very narrow and specific voltage range, so that as you decrease the voltage being supplied the amount of current increases through both power supply and LED electronic components. This will destroy your power supply, your LED light and could start a fire in your house.
Actually, in this case, according to Ohm's Law, the opposite is true. LED's are current limited by resistors to a certain maximum voltage they are designed for. Lower the voltage and you will lower the current. Increasing the voltage will increase the current.
V=Voltage, I=Current, R=Resistance
in this case R= 12/.033 -- R=364 ohms. Using this figure lower the voltage and see what happens.
I=10/364 -- I=.027 amps of current.
The end result will be lower light output from the LED.