"The rear panel of the PCM-80 provides balanced inputs and outputs on 1/4-inch TRS jacks. A 2-position INPUT LEVEL switch, 20dB/0dB, accommodates both balanced and unbalanced input levels. There's S/PDIF digital I/O, and the digital inputs can be mixed with the analog inputs! A 1/4-inch TRS FOOTSWITCH jack enables connecting two footswitches to the unit. The 1/4-inch TRS FOOT CONTROLLER jack is for a footpedal. MIDI IN, OUT, and THRU jacks and the power connector complete the rear panel." - rapmag.com