A system (10) for sensing electrophysiological signals includes a plurality of shielded electrodes (12). The electrodes (12) are connected to an amplifier (18) for amplifying signals received from each of the electrodes (12), the amplifier having a shielding input and the shielding of the electrodes (12) being connected to the shielded input of the amplifier (18). A power supply (22) powers the amplifier (18), a reference voltage derived from the power supply (22) being used as a reference voltage for the electrodes (12).
