Once Newegg gets some more in, I'm going to order myself a pair of Sennheiser HD485s. I will be using them with my Audigy 2 ZS. My question is, do I need an amp? I'm not exactly sure what the purpose of amps is or what they really do. Will my headphones sound better with an amp? If so, what is the price range of a good, solid amp? I've seen what looks like home-made amps around here, and if that's all I need, I would be more than willing to purchase one from someone here. Thanks for the help.