Built-in: 1/4" headphone out. For other I/O the Duet2 requires either a breakout cable (2 ch analog in on XLR/TRS combo for line/mic/instrument, 2 ch analog out on 1/4") or breakout box (2 in on XLR, 2 in on 1/4", 2 out on XLR). OLED touchscreen, multi-function knob, phantom power.