You could use those out puts for all kinds of things. Like maybe you would take 1 and 2 and use them to send a stereo mix to your monitors. You could send 3 and 4 to a tape deck. You could use 5 and 6 to send out to an amplifer in another room, like a listening room.
I use mine this way:
1-2 go to the amp which powers my monitors
3-4 go to my stereo headphone amp
5-8 go to the mono inputs on my headphone amp and I assign in the Aardvark software particular instruments to them. So the drummer says he wants more bass.... I assign the bass input to output 5 and jack that up on the headphone channel assigned to the drummer. The singer wants more of his voice....
You get the picture.
When I got my Q10 I thought, "What the F^(# am I going to use these for?" But I find my self using 6 to 8 of them anytime I record a group of people.