A system for driving a plurality of loads each connected to respective signal terminals and to a shared common load terminal. Multiple conventional signal amplifiers each provide a content signal at one of the signal terminals. The signal amplifiers each have a primary-power upper terminal, to receive a first voltage (V1) from a first power supply, and a primary-power lower terminal, to receive a second voltage (V2) from the first power supply. A bias amplifier biases the common load terminal, and has a secondary-power upper terminal to receive a third voltage (V3) from a second power supply and a secondary-power lower terminal to receive a fourth voltage (V4) from the second power supply, wherein V2≦V4