A DC power supply and a method for operating a DC power supply, wherein the DC power supply comprises at least one feedback-controlled preregulator, at least one feedback-controlled postregulator supplied by the feedback-controlled preregulator, output terminals for supplying regulated constant current or regulated constant voltage to a load, and a control unit for controlling at least one of the feedback-controlled preregulator and the feedback-controlled postregulator, and designed for adjusting a voltage offset or a current offset added to a signal in a feedback loop of at least one of the feedback-controlled preregulator and the feedback-controlled postregulator.