Tonally, I find these to be more accurate than the K501 because they have more generous bass. The rest of the qualities of the 501 still hold true however, and these are quite clinical and uninvolving with most types of music other than Classical. They do respond well to a warm powerful headphone amp but not enough to change their fundamental character. They lack a little air and treble extension of the 501s too, but I would still choose them as the better value.

These represent a very good bang for the buck. Though not for bassheads, they are well balanced headphones, with incredibly sweet mids and very nice soundstage. I think they could be more detailed, however. They are very comfortable. They're about as close to full size Etymotic 4S's that I have heard.