As far as I know, most phones are designed to not need an amp. High-end hifi phones are a different matter. The DT880s I'm thinking of getting apparently do need amping, but then, some high-end soundcards (Xonar Essence STX) now have proper headphone amping built in.To those people using headphones, do you use a separate amp? I don't see how headphones could possibly sound very good running straight off the line-out.