DJ software

[EMAIL HIDDEN]

hi guys,

me and a friend want to play some music (as deejays) in a small
bar. software like iTunes would be enough if only we could do
some pre-listening

so i was thinking if i take along my M-Audio firewire thing and use
this for the primary output and use the built in headphones interface
for the pre-listening...

is there (open source) software for the mac that can do this or can
iTunes be tweeked so it does this?

---
perry