Abstract: The disclosure describes improved apparatus for driving a load, such as a meter, in proportion to a source voltage produced by a signal generator. The apparatus includes a non-differential gain stage for generating an amplified voltage between a gain stage output and one of the generator outputs. The non-differential gain stage is followed by a differential stage which generates a rereferenced voltage between the differential stage output and one of the load terminals. The rereferenced voltage is proportional to the amplified voltage and is substantially independent of any offset voltage between the one generator output and the one load terminal. By coupling the rereferenced voltage to the load, the load voltage is made proportional to the source voltage irrespective of changes in the offset voltage between the one generator output and the one load terminal. The load may include a meter and an amplifying stage for ranging and zeroing the meter.