Both of the IO’s have ADAT lightpipe inputs. Each ADAT digital connection can work with devices that allow up to 8 inputs at sample rates of 44.1-48kHz. You can use a product such as the Alesis AI3, Presonus DigiMax, Focusrite Octopre, interface to convert an analog input to a digital output via lightpipe. The S/PDIF connection provides another stereo input.