I think I know the question, and it's about the suitability of the Mackie Onyx series as a DAW front end.
The firewire main outs are described as 'post gain, pre-insert, pre-EQ, pre-mute, pre-fader.' which means the only control you have over what's going thru the Onyx is a simple gain control and nothing else. Also, the only thing you can bring back thru the Onyx is the 2-channel stereo main mix from Tracktion, Cubase or Sonar...
These are SERIOUS handicaps, and Mackie should have known better than to promote this mixer as anything but what it is - a live board with a nod toward the computer recording world.
To sum up, Mackie did NOT minimize our excessive gear. With a different design they could have, but the Onyx just doesn't fill the bill.