[wags1533]

hey everyone. im new to headfi so im still getting the hang of things. i am a new/intermediate audiophile and am looking to get a pair of grado sr80i cans. I currently have koss porta pros and a pair of shure shr440's for studio purposes. my friend has a pair of the grados and i love them. i was wondering, one, is it nesscesary to have an amp (if so preferably portable) and is it possible to change out the ear cups?
 
thanks for the help,
wags1533
 
p.s- if anyone has a suggestion of another pair of cans for the 100-200 price range that would best the grados, please let me know.