The present invention, generally speaking, uses multiple selectable power supply paths, a saturation detector, or combinations of the same to achieve efficient power supply processing. In one aspect of the invention, a power supply processing circuit includes a first switched converter stage and a second linear stage. Depending on the power supply desired, the first stage may be bypassed to avoid conversion losses. In another aspect of the invention, a saturation detector is used to control the first stage such that the second stage operates efficiently just short of saturation, thereby avoiding distortion.