iTunes with audio interface

I have a Firebox audio interface. I can choose to put all my system sounds through it, this works fine.

I also have some music production software that lets me select the audio interface as its output. This way I can make music with my headphones while my daughter watches teletubbies youtubes on my lap with the imac internal speakers.

So it's obvious that the computer can deal with different audio outputs simultaneously, so how can I make it so iTunes comes out of my audio interface but other system sounds come out of the speakers/headphone jack as normal?

Message was edited by: dan lett