The Discrete 4 offers four Class-A preamps that provide console-grade sound. All of them utilize combination XLR-1/4" connections, but two of them are specifically designed to switch between mic level, line level, and Hi-Z sources. Monitor outputs and two pairs of line outputs can be found on the back of the unit, as can thunderbolt and USB ports for connecting to computers.
S/PDIF and ADAT are both provided over optical I/O. The unit is expandable over ADAT, giving you up to eight extra channels. This is Antelope, so you'll find their top-notch 64-bit acoustically focused clocking on the unit, and you can sync the Discrete 4 over BNC connections, or distribute clocking to other units.