Hi... I'm new, and I'm here with a question for you all. I bought a Sennheiser DSP 360 off of eBay, since I use my PowerBook G4 to listen to all of my DVDs. I want to hook it up to my PowerBook, but I can't figure out how. My PowerBook has a standard minijack soundout headphone port thing, and the Sennheiser just has 4 RCA ports in the back. Is there some sort of adapter I need to purchase and if so, what?