The HD 700 has a 150-ohm-rated impedance, as opposed to 300 ohms for the flagship HD 800 headphone. Even so, 150 ohms is higher than most headphones designed for use with portable music players and phones, typically rated at 50 ohms or less.
The HD 700 doesn't fold up for compact storage and isn't designed to withstand the stresses of being jammed into a travel bag too many times, so it's really a stay-at-home set of headphones.
The HD 700 comes with a two-year warranty, and proof of purchase or sales receipt from an authorized dealer is required for warranty claims.
The HD 700 is equally adept playing movies and music, thanks to its unfatiguing sound. Resolution of fine detail is in the top tier of high-end headphones, and yet with good quality recordings, the sound is never harsh or unpleasant in any way.
The HD 700's wide-open soundstage floats freely from the earpieces, so I found it easy to forget I was wearing the headphones after just a few minutes into watching "Being Flynn" on DVD. The sound isn't confined within my head, rather it appears to come from further away.
The film stars Robert De Niro as a homeless man, and the HD 700s let me hear subtle details of the actors' voices better than I do over most high-end speaker systems. When De Niro is out on city streets, the traffic sounds come from off in the distance. The HD 700's neutrality is especially evident with dialog; voices sound naturally balanced and clear.
Outrageously powerful soft-to-loud dynamic jolts, like in the plane crash scene in the "Flight of the Phoenix" DVD are communicated better than they are with most headphones, but nowhere as well as big speakers and subwoofers. I'm using an Onkyo TX SR805 AV receiver for these music and home theater listening tests.
For music listening, I switch over to the Schiit Lyr headphone amplifier ($450). The deep rumbling basslines on my "French Dub Connection" CD are given their full due by the HD 700.
With great headphones like these you don't just hear the bass, you can sense the very texture of the sound. My Grado RS-1's bass is just as powerful, but it's looser and less clear. The RS-1 also shrinks the recording's soundstage, collapsing it inward, so it's trapped between my two ears.
On fusion jazz recordings, funky electric bass notes sound blurred over the RS 1, and more crisply defined over the HD 700. When the drummer whacks a snare drum, the HD 700 will make me jump; it's that alive and realistic sounding.
The HD 700's refinement also shines with classical music. The headphone almost disappears and lets the music come through without adding any coloration to the sound. The quiet details, like the room sound and ambience of the recording venue are presented with unerring accuracy.
The Sennheiser's clarity is hard to resist, especially compared with the Hifiman HE-500 ($799) headphone. The HE-500 has a richer tone, which some listeners may prefer, but in the end the HD 700 sounds more like being there, and it's considerably more comfortable than the HE-500.Previous generations of high-end Sennheiser headphones didn't sound great plugged into iPods and such, but the HD 700's winning clarity is on full display on my iPod Classic.
The HD 700 is very expensive at $999.95, but its extraordinary sound, build quality, and comfort justifies its lofty price tag for the most demanding audiophiles. They're highly accurate and clear, but won't likely satisfy buyers seeking a rich and warm tonal balance. Regardless, no single set of headphones can please every taste, and the HD 700 will appeal to those buyers who prize clarity and sonic precision.