Surgical generator systems and related methods are disclosed herein. An exemplary generator system can include one or more auxiliary transformer stages to boost the amount of power applied to low-impedance tissue, or to adjust the output voltage and current delivered to a surgical instrument. The auxiliary transformer stage(s) can be disposed in the generator, in the surgical instrument, and/or in an intermediate component. Exemplary generator systems can also include an accessory box disposed inline between a generator and a surgical instrument to provide expanded functionality to the system. The accessory box can have a ground plane that is isolated from the ground planes of the mains supply, the generator, and/or the surgical instrument to reduce or eliminate patient leakage current.