how to use external speakers with itunes?

just wondering, im thinkin of picking up some monitor speakers soon, yamaha hs50m if anyones interested. these will run through a m-audio fast track pro.

although not the intentional use for them, i'd like to play my music through them for abit of extra volume. is there a way to route itunes music through those speakers instead of the built in speakers?

thanks

spot on, thanks mate