Abstract: A reliable, safe, accurate, low noise, inexpensive, portable amplifier circuit is adapted to accurately amplify both AC and DC neural response signals. A patient or subject is electrically connected to a multi-channel system for electrically measuring the patient's AC and DC neural response signals at a plurality of locations using electrodes connected through a multi-electrode cable. The neural response signals are input to a digital DC amplifier to filter, amplify and digitize the neural response signals. Digitized neural response signals are converted to optical signals and transmitted via a fiber optic cable to an interface that is preferably connected to a patient stimulus generator (e.g., a Ganzfeld stimulator or pattern stimulator for multi-focal ERG). The system also includes a stand-alone computer such as an IBM® compatible Personal Computer (PC) for two-way communication with the interface via a standard data interface cable (e.g., a USB cable).