I would hope that this would be possible, but at the moment I have no idea where to go about setting it up. What I would like to do is use the Line-In on my Powerbook for realtime playback of another audio source. In my case, I have several Audible Audio Books stored on my iPod, but Audible says 3 systems only. I have my Mac Mini with eyeTV as one, my 24" iMac as a second and my lady's macbook as the third. However, when I am on the road, I would really like to listen to my stuff on some speakers instead of on headphones. So, is there a way to use a 1/8" Mini strait through cable to plug from my iPod into my Powerbook's line-in port to listen to these audio books on my speakers and get around the whole 3 system limit with Audible? I can get System Preferences -> Sound -> Input to see that there is something coming in there, but I dont want to record, I want to hear. Any help would be greatly appreciated.