Safely tucked away at the back of the S1 MkII, in addition to the CV inputs, the three MIDI ports and the CV output jacks from the MIDI-CV converter, are various 'set and forget' switches, such as the calibration pots for the Oscillators, Master Scale, and main CV input, and the four-way DIP switch with which the receive channel for the built-in MIDI interface is adjusted. Thoughfully, the 16 possible combinations are silk-screened onto the panel, so you don't have to go hunting through the manual if you ever want to change the main MIDI receive channel.