We directly compared the Sennheiser CX 300 to Etymotic's ER-6i ($150) in-ear headphones and came away impressed with the little Sennheisers. First thing, the CX 300's bass went as deep as the ER-6i's, but the vocals and guitars on Ryan Adams's mostly acoustic new CD, 29, were noticeably less "canned" and hollow-sounding on the ER-6i. The CX 300 rocked out with a live version of the Rolling Stones's "Start Me Up," and the band's power and grit were all there; the headphones definitely played loud enough when paired with our iPod.
Sennheiser's off to a good start, but the CX 300's sound is nowhere as clear and open as that of our favorite Shure and Etymotic models.