If you want a set of analytical sound in-ears, look no further than the Head-Direct HiFiMAN RE252s. They simply blow anything else out of the water in terms of details in the midrange and frequency response.
Definition across the spectrum has been elevated sufficiently to warrant the price difference between it and the RE0s which are good in-ears, but they are clearly outshined in all areas by the new RE252s. The midrange bears a cruel amount of details and puts even the more expensive dynamic based Sennheiser IE8s to shame in this aspect, which is no easy feat for a set of in-ears that cost almost a full $100 less.
The fit one can achieve with the RE252s is just amazing, these universal in-ears are the most comfortable I have worn to date. Actually the fit is so good that it rivals that of my custom in-ears because they are soft, so they tend to irritate the ear even less than a set of hard custom in-ears when you move the ears slightly when for instance opening ones mouth.
Brilliant fit still proves to be an elusive goal. For me the RE252s fit snugly because I am able to use them with a set of single flange tips. I have read reports at Head-fi that some users experience a hard time getting proper fit to start off with, but somehow solve it along the way. To me the new design seems to force the fit a bit, because you do not get the option of running the cable over the top of your ears, however, at the same time the silicone shell works like it should, at least for my ears (which are pretty normal, both size and shape wise for a European). Achieving a good fit is somewhat enigmatic with the RE252s, best advice is to take your time, the reward for doing so is plentiful.