1 ch analog in (XLR mic or XLR line or TRS line or 1/4" instrument), 1 analog out (XLR or TRS), insert (2 TRS), tube mic preamp, tube compressor/limiter, 3-band EQ, various digital i/o on optional cards. USB connection requires DI-MOD USB option ($449 list), which adds A/D to this analog device.