I know this is a bit early, but hey. I had tried to plug a guitar into my mac before, but it never worked because all I have in a line input, not a mic input, so I would always have to borrow a preamp. However, with GarageBand and the software amp in it, would this be required, or can I just plug it in and have it work as my preamp? Same with a microphone, although there was nothing mentioned about any other built-in amps. Or is there some other software that I can use to boast the input, or am I going to have to resort to buying a sound card or an iMic or something similar?