The audio connection dialog allows you to specify to what soundcard to write output to or read input from. This can be modified either by assigning single channels or in bulk mode.
Select the desired soundcard and don't forget to click enable. In order apply your modifications. After click OK.
The output connection tab allows you to link a bunch of channel at once.
Select the desired soundcard and don't forget to click enable. In order apply your modifications. After click OK.