Hey guys, I'm very knew to this audiophile stuff and I have a few questions. First of all, I currently own a set of Sennheiser HD280 Pros, I use mainly my Ipod Classic 80gb and my computer for listening to music, I use a M Audio Mobile Pre USB for sound on my computer (I don't know if it's a DAC/Amp), and most of my music is either 256kps AAC or 320kps MP3. My first question is, is my M Audio a good set up for my computer? Also, do I need an Amp or DAC for my Sennheisers, or will I even be able to tell a difference? I know these might sound very simple, but I am totally overwhelmed by all this audio stuff that I've never heard of. Thanks!