Auxes or Buses can be linked together for stereo out. If for example, we wanted to link Bus 1 with Bus 2, we can achieve this by following this path:


The Buses window will open, from here you can see that selecting the yellow Bus 1 and Bus 2 tab, the faders are independent from each other.

If we now select either of the yellow Bus 1 or Bus 2 tabs, we can go over to the Channel / Channel Input and select StereoLink

Now when we select either Bus 1 or Bus 2 fader we will see they are linked and move together. 

If we wish to to reverse this and return back to normal we follow the same path and deselect the StereoLink option.