For my recent birthday I was given headphones that have been specifically designed for the ipod/iphone by B&W. This company has long been a favourite as they produce astonishing speakers. I bought a pair of B&W speakers 25 years ago, they are still being used and they are still amazing.
If you really, really enjoy listening to music and you want to splash out on state of the art headphones then check out the B&W P5’s. You will not be disappointed.