I am not sure whether i'm buying an amp or not, I would like to have headphones that are also quite good without an amp, so I can buy headphones now and possibly an amp later, amp budget would be around 100 euros which is about 135 dollars currently, but as i said I am not sure about the amp. I am still not sure which headphones to pick though, I am considering the HD 598, and DT 770/880. How good are these and how does the impendance 32,250 or 600, affect the DT 880 in terms of sound quality and the necessity of an amp?