The FADER knob is the channel fader, with the ability to insert an external fader from the rear panel.
The PAN control is a standard stereo pan circuit with a center detent.
The INSERT button can act as a balanced insert for outboard equipment, or it can be used as a MIC PRE/TAPE PLAY switch for live recording to check the mic pre output and then the output of the machine for confidence checks or post recording playback without repatching anything.
The ST button turns on the stereo bus, which allows the module to send to the aux sends without going to the stereo bus.
The Polarity switch is a standard phase inverter for the main signal path.
The 4 sends are internally configurable for PRE or POST fader signal. The MX2 has an optional DIRECT transformer output.