Etymotic has tuned these ear-canal phones for the iPod generation: The ER6i's have greater sensitivity and more bass than the ER6. They come with three-flange rubber eartips and foam eartips. Since a tight seal is critical to good bass performance, the foam tips were more effective and more comfortable. Foam eartips are a minor inconvenience, though, because you have to compress them with your fingers before inserting them, then wait until the warmth of your ear expands them. We prefer the Etymotic foam eartip material to that of the Shure E3c/E4c. Replaceable filters protect the drivers from ear wax and provide damping to smooth out peaks in the drivers' response.

The ER6i's are highly effective at blocking outside noise. We heard brilliant clarity throughout the audio range, but we had hoped for more bass. The ER6i's respond well to EQ, however, and a little bass boost or loudness compensation brings the bottom end into line. During testing, we heard buzzing in one ear on bass notes; a filter was loose. We pressed it back in, and all was fine. Quieting: 12 dB; Frequency response: Smooth and bright; Comfort: Very good.