An apparatus, method and system for collection of physiological electrical potential signals. In one embodiment, an apparatus for use in measuring electrical potentials in a subject (e.g. an animal or a human), having an amplifier being removably mountable to a ground electrode and electrically coupled to at least two signal electrodes, wherein the amplifier is configured to communicate with a signal processing device and indicate if one of the at least two signal electrodes is poorly affixed to, or detached from, said subject. In another embodiment, the at least two signal electrodes comprise a first signal electrode and a second signal electrode, and the amplifier is configured to detect differential electrical potential signals presented by the first signal electrode and the second signal electrode, amplify the differential electrical potential signals by a predetermined gain level to generate an amplified signal, and transmit the amplified signal to the signal processing device.