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At first glance, the Sennheiser PXC 300s looks like upscale Walkman-style headphones; closer examination reveals them to have an impressively durable design. The earpieces are approximately 1.75 inches in diameter, so they can't completely cover your ears, but the PXC 300s' extraplush leatherette ear cushions blocked out a significant level of noise on their own. They exerted a fair amount of pressure on our ears, but we found the headphone extremely comfortable, even in hot weather. The headphones employ Sennheiser's proprietary, spiral-embossed Duofol diaphragms and bass-tube technology for improved sound quality. The PXC 300s are backed up with a two-year warranty.
Sennheiser claims its latest NoiseGard Advance system eliminates the electronics' inherent background noise, but we heard very low-level hiss in quiet locations; in the noisy world, the hiss was inaudible. Sennheiser also claims the PXC 300s reduce susceptibility to interference from cell phones and other radio-frequency sources, and we experienced no disturbances. The PXC 300s' noise-canceling circuitry and two AAA batteries are housed in a separate 5.25-inch-long, black plastic tube fitted with a metal belt clip. Sennheiser states the batteries should provide up to 80 hours of service, though you can still enjoy music over the PXC 300s even if you don't have a spare set of AAAs on hand; you just won't get the noise-canceling capability if you have no batteries. The cable running from the headphone and the battery case is 4.5 feet long; it's fitted with a 3.5mm stereo plug compatible with virtually all portables, and you get a 6.3mm adapter for home use.
Sennheiser also offers a less expensive alternative, the PXC 150s ($130), which forgo some of the PXC 300s' design features. They won't play as loud and produce more limited bass response, but the noise-canceling abilities are identical.
We evaluated the Sennheiser PXC 300s' noise-canceling (NC) performance on New York City's subways and buses. The din reduction wasn't up to the standards set by full-size headphones that completely enclose the ears, but it's definitely in the ballpark. Engaging the NC circuitry significantly boosted the PXC 300s' volume level and accentuated the midrange frequencies, which heightened the apparent NC effect. That volume gain was also appreciated because the PXC 300 wouldn't play particularly loud with our iPod. Sound quality was above average, with good bass power and definition. The PXC 300s, like many other noise-canceling headphones, produce acoustic pressure on the eardrums. Listeners sensitive to this effect may find it mildly uncomfortable.
We compared the Sennheiser PXC 300s with one of our favorite NC models, AKG's K28 NCs ($160). The Sennheiser's sound was clearly more detailed with superior bass definition, but the AKG produced more bass and could play a lot louder than the PXC 300s. Noise-canceling abilities on both 'phones were excellent.