The Tesira EIOC-4 expander card is an optional card that can be installed in the Tesira EX-MOD and all Tesira amplifiers. Each EIOC-4 provides two channels of mic or line level audio input and two channels of mic or line level audio output. The inputs and outputs are electrically balanced and provided on plug-in barrier strip connectors. Software control of each input includes gain with clip indicator, +48V phantom power, mute, level, and signal invert; whereas control for each output includes mute, level, signal invert, and full-scale output reference.