Bel Canto USB LInk 24/96 and iTunes on MacBook Pro

I'm new to PC Audio and need lots of help. I connected the Bel
Canto USB Link to my Apple MacBook Pro and to the RCA Digital Input of my Audio Logic DAC. When I go to Audio MIDI Setup in iTunes, the Bel Canto USB Link shows up in Audio Devices and when I click on Configure Speakers for Stereo I get a test tone from my left and right main audio system's speakers. However,when I insert a CD or play a ripped CD on iTunes, I only get sound through my Macbook speakers instead of my main audio system's speakers. Is there some kind of setting I'm missing in iTunes?
Your help is much appreciated.
Go to the Mac's System Preferences > Sound and click the Bel Canto ( the default is Internal Speakers) first..there is nothing you should have to do in iTunes. In fact, the Mac "should" recognize the Bel Canto without have to go to Sound, but sometimes it need a little help..
Thanks Jb8312. It worked. Listening to my pc through my main system. Sounds pretty good.