A dual asymmetric input power supply architecture for use in power systems employing input power source redundancy. The dual asymmetric input power supply operates from a main input of the power supply when acceptable voltage is present on the main input. If the main input fails or is out of tolerance, power can be supplied from an auxiliary input through a transformer isolated switching converter. The dual asymmetric input power supply architecture maintains the high efficiency of a single-input power supply while providing an auxiliary connection for input power source redundancy.