A power circuit include a plurality of LED strings, each LED string having multiple LEDs connected in series. A plurality of magnetic amplifiers, reset current sources, and a control circuit are used to drive each LED string with equal current and to independently regulate the amount of voltage supplied to each LED to maximize efficiency. One magnetic amplifier, one reset current source, and one current sink are dedicated to each LED string. The control circuit measures the voltage drop across each LED string and determines an amount of reset control current in response to the measured voltage drop. The reset control current is supplied by the reset current source to the magnetic amplifier dedicated to the regulated LED string. The amount of reset control current supplied to the magnetic amplifier dictates the amount of voltage supplied to the LED string.