1.Make sure no applications are running.
2.Go to your Sound Control pannel. (in MacOS 8.6 , go under the apple menu ,then to control panels ,and then choose "Monitors and Sound" , In Mac OS9.x ,go under the apple menu ,then to control panels ,and then choose "Sound".
3.Then choose the "Sound Out , or Output" tab (whichever you have)
4.Notice that it is currently set to "Built In"
5.Choose "PCI-324"
6.Close up the Sound Control Panel.
7.Now when you playback your Mac sounds or any other program that would normally come out of the built in speaker , it will now come out of the Motu Hardware.(Usually out of its Main Outs)
8.If you didnt have "PCI-324" as a option in your Sound Control Panel , you either have the PCI-324 Sound Manager Diver turned OFF ,or not loaded.You can install it with your Motu install CD.(Choose PCI-324 Sound Manager Driver in the Custom Install Screen)

WARNING!!!! Doing this may cause your Audio application to throw the error message:
hardware is either not installed , or is in use by another application"
In this case you must Undo the above! (Reselect "Built In" and RESTART the CPU!!)