I bought the MX500's to replace my ipod earphones. Like some of the other reviewers I don't consider myself an expert but I know what I do & don't like. And I didn't rate the ipod earphones at all! The quality of the music I was listening to was really poor - tinney and nowhere as smooth as I would like.
Anyway, the MX500s are great - especially for the price. If you want a better sound from your much cherished ipod and don't want to spend a ridiculous amount on the new ones, then these are for you. The sound is much more smooth - the bass particularly sounds better in my opinion. I felt the bass on the ipod was similar to the sound of bass from a vibrating speaker - not good.
Also the MX500s come with a small volume control on the lead. It doesn't make major changes to the volume but it's better than nothing. It's a great addition in my opinion as I hated having to search into my pocket to adjust the volume, or worse taking the ipod out to adjust it & then getting it nicked!!