sennheisers typically have good quality audio but severely lack low end bass. sony xb typically have high bass but muddle everything else. at least this is true for all conventional headphone offerings. i'm not so sure about the in ears.
what about the klipsh s4 or audiotechnica ath-im50?
cant say i've used any of those in ears. mainly i've used ipod headphones (which really arent bad for the price) or cheap gummy headphones since i can replace them every month (they get nasty when using headphones at the gym). i have used those brands in normal over the ear headphones though.
anyways. not really what you wanted but perhaps it gave you a few more options
(oh and is there any reason why you arent using over the ear headphones?)