I had been using my HD580s simply powered by my soundcard (Audigy2 ZS) for a while now, and while I knew I wasn't getting the full quality these cans are capable of, I figured it wasn't too bad since I don't listen to my music very loud. Nonetheless, my dad bought me a cheap little headphone amp for Christmas, and I'm amazed at the difference. If you have a pair of these guys or similar headphones and are running without an amp, shell out the money for one, even just the cheap one I have makes a huge difference.