All eight of the OctoPre MkII's audio inputs use Neutrik Combo connectors. These can accept male XLR connectors, TS (un-balanced) and TRS (balanced) jack connectors.
If an XLR cable is used, then the pre-amp will automatically set to microphone level. If a Jack cable is used, then the pre-amp will be at line level. For instrument signals use a Jack cable connected to input 1 or 2, and press the Inst button to switch to high impedance instrument level.