In Pro Tools 9 you will have to select what device you would like Pro Tools to use for sound input and output.
1: Launch Pro Tools 9
2: Click on the Setup menu at the top of your screen and drag down to Playback Engine.
3: At the top of the Playback Engine window click on the Current Engine drop down box and choose your device.
Note: Make sure that you have downloaded and installed the latest driver updates for your device.