I have a Macbook Pro and I want to be able to carry it to a friends' house and record some of our jam sessions. Is there a way to record several guitars, some vocals, and a harmonica all at the same time into Garageband? Can they go in as different tracks so I can adjust them later? If not...can I buy a cheap mixer and connect it to a USB interface like a Line 6 or M-Audio Fast Track which will feed the audio into Garageband? Thanks in advance!!!