I think over ears are better for sound quality. SE215s have great bass and sound quality for a cheaper IEM. Then again it may not be enough bass if you are looking for XB500 amount of bass. Like TMRaven said, the bass is like that because they blast it over the mids/treble and highs. There is a balance to the charts, and blasting up the bass is going to give you the loss in the other parts of the freq. IMO though, Denon D5000/7000 have SICK bass while holding onto some great quality.( but even these suffer in the other freq. due to the crazy bass. not so much the d7000s though)
This