I am also thinking of getting HD 600 or 650. I heared that the 600 bass have more attack but the 650 is more like "boom". I only have Fidelio x2 but the treble on medium volumes is too much for me so i want something more neutral. I am listening all kind of music, everyting from the 80s pop to metal. I hear the 600 is more relaxing and easier to listen to fora longer periods. How does the 600 handle all that? Also, i am curious since these headphones gets a lot of praise and i want to hear why.