i beg to differ here. i got my PX200's right when they came out, so i'm still not sure if sennheiser has changed them since i got mine, but to my ear both the PX200's and MX500's sound very similar. there are two main differences, however, which can decide which are better for your needs. first, the MX500's are much clearer, making them better for soft acoustic strumming and other similar music. the PX200's, however, counter by having better impact. not necessarily better bass, but the fact that they're bigger cans just give em a bit more slam for rock and rap. so if you listen to light stuff, go with the MX500's. if you listen to rock, go with the PX200's. if you listen to both soft and loud music, get the PX200's. they're more versatile sonically.