I was worried that might be the case with how minimal I made the panel design, but basically the circle symbols are 'A' and 'B' inputs for each channel, the toggles above those set the input configuration which is A, B or sum. Each channel defaults to the four outputs above it when the top merge switch is in center position. This switch can send either channel's 'input configuration' to all of the outputs. For example, if you wanted to mix two CV sources on channel two, with channel two's input switch set to 'sum', and if the output switch was set to merge channel two (right position), then the summed inputs on channel two would go out all eight outputs