The 8c can be connected to either digital (AES3) or (balanced) analog sources. It has a male XLR input that can be used to present these signals to the 8c. Make sure the correct preset is selected. The 8c has a -10 dBV analog input, a +4 dBu analog input and an AES3 digital input. Consumer grade equipment with a relatively low output voltage usually works best with the -10 dBV setting. Professional equipment with a higher output voltage usually work best with the +4 dBu setting. AES3 digital input is for use with digital sources with a balanced output, AES3 or AES/EBU.
Unbalanced sources can be used with the 8c, but proper functioning with regard to hum and noise is not guaranteed. Dutch & Dutch recommends that balanced sources be used in order to obtain optimal gain and sound quality. If the unbalanced equipment is properly designed and grounded, an adapter cable can be used. Within that cable pins 1 and 3 should be connected together.