Each pair of outputs (1/2 - 9/10) can be assigned its own unique mix of both the four input channels and 10 channels of audio from the recording software in use (Logic, Cubase, etc.). These mixes are created in stages: First, the input channels are balanced, for example if you want a little more of input 1 than 2 and even less of inputs 3 and 4 (the signal connected to the SPDIF In) going to the main monitors then you simply set the levels of the inputs accordingly in the IN 1/2 BAL section of outputs 1/2. This then becomes the INPUT MIX for that stereo output pair. If you only want to hear this signal with no pre-recorded audio from your sequencer then set the slider in that section to the extreme left position. The mix of pre-recorded audio coming from you sequencer is called the PLAYBACK MIX and is set generically across all outputs using the faders in the top right of the SaffireControl window (S/W 1/2 - 9/10). Alternatively, a custom P/BACK MIX for each pair of stereo outputs can be set in the corresponding section. This way, if one artist wants a little less drums or a little more bass compared to another then it is easy to achieve. To blend between amounts of the INPUT MIX and the P/BACK MIX on a stereo output pair, simply use the slider in each output section.
A CUE MIX is another name for a HEADPHONE MIX. There are two main HEADPHONE MIXES/CUE MIXES in SaffireControl, which are outputs 5/6 (Headphone 1) and outputs 7/8 (Headphone 2). If even more headphone mixes are required by the engineer then outputs 3/4 could be sent to a distribution amplifier, so technically 3 unique headphone mixes are achievable.