[This review applies to the Shure E2c, Etymotic ER-6, and ER-6i.]
These three in-ear-canal models stake claim to the middle ground--in terms of sound quality, noise isolation, and price--between the Sony MDR-EX71 on the low end and the higher-priced Shure E3c and E5c and Etymotic ER-4P. All three block out significantly more external noise than the EX71 and preserve more of your music's natural detail. However, like most true in-ear-canal models, you get less of the visceral bass that you find in "standard" headphones -- it's there (provided you get a good seal), but you hear it rather than feel it. This takes some getting use to for most listeners; some never get used to the experience.
Comparing the three, the Shure E2c have a bit more bass and less detail than the ER-6, whereas the ER-6 do the midrange and treble slightly better. The ER-6i are our favorites here -- and gain our Editors' Choice rating -- providing the most balanced sound as well as an iPod-matching white design.--Dan Frakes