• Lightweight aluminum voice coils for very fast transient response
• Specially designed acoustic silk ensures precision damping over the entire frequency range and helps to reduce THD to an incredible 0.05/li
• Improved frequency response is 10 - 39,500 Hz (-10 dB)
• Hand-selected matched driver elements

With no need to reinvent the wheel year in and year out, 2004's titanium/silver-colored HD 650 is only the third top-of-the-line incarnation since the HD 580, following the classy HD 600 (and not counting Sennheiser's made-to-order $15,000 Orpheus electrostatic headphone). Is each issue better than the last Fundamentally, yes, though they're also simply "different." Taking as a starting point that each is truly excellent, the 580 might be said to focus on glorious midrange; the 600 makes a point of delivering extended, exceptionally airy high frequencies; and the 650, fittingly enough, tackles the most difficult area of sound for small drivers to handle: deep bass.

The 650 offers appreciable bass well below 40 Hz, the region responsible for the deepest frequencies generated by kick drums, timpani, double bass, electric bass guitar, and all manner of electronic sounds. Further, the 650 reproduces its low frequencies with only minimal emphasis in the upper-bass region, between the areas we commonly call "bass" and "midrange", in which undue emphasis can destroy clarity both above and below.

If you listen mostly to classical, jazz, and acoustic music, you'll probably embrace the headphone's low-end authority without reservation. If you listen to contemporary pop/rock and electronica, however--genres subject to a fair amount of equalization and bass boosting over the course of recording, mixing, and mastering--then you might find yourself facing, at times, a bit too much bass. Of course, most rock demands excellent bass response, and the HD 650 delivers. It just isn't forgiving of a musical production's gross errors of judgment, which would makes it a...