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The HD800 arrives in a quite massive fabric-lined presentation box accompanied by three full-color brochures—one in German, English, French and Spanish; one in Portuguese, Turkish, Italian and Dutch; and one in Russian, Polish, Chinese and Korean—to address a global audience. The introduction of the text makes proud mention of three individual patents which cover specific parts of this statement assault.

The center of the steel headband sports the engraved serial number which entitles the owner to a printout of that unit's individual diffuse-field frequency response chart from Sennheiser.* Adjacent to this number are calibration markers to assure that widening or narrowing the ear cup spacing occurs symmetrically along the ten possible click stops per side. My skull was comfortably accommodated when the band showed six markers per side. The HD800 will hug even very swollen heads.

Sennheiser then issues a very real warning: Due to uncommonly low distortion from these headphones, you're liable to listen far louder than usual. It's very true. If you treasure your hearing and mean to avoid fatigue, don't.

* You post this request by e-mail which will be confirmed by a reply like this: "The frequency certificate of your HD800 will be dispatched by post according to the information you supplied. Please be patient for 2 to 3 weeks. This confirmation doubles as proof that the 2-year warranty from your date of purchase has been activated..."

Let's quickly return to the warning. As the photo in the owner's manual at left shows, the HD800 transducer really is big. This translates into lots of moving air mass very close to your ear drums. Crank the volume and you're not far off from sticking a blow dryer into your ears.

It's not distortion that tells you when things get too loud. It's physical discomfort. Depending on how sensitized—or not—you are to to this bio feedback will determine how soon you experience it and whether you'll blame the HD800s or yourself.

You'll likely discover that the line between happy hour and excess is quite specific. Simply pay attention. For most, this will be new territory. There hasn't exactly been a headphone like this before.

As an open-backed rather than sealed design, the HD800 is not suitable if you wish to—or must—listen in complete privacy. People three or more meters away will be exposed to your sound leakage.

If you approach the HD800s from sealed headphones or even the HD650 predecessor, you'll notice right away that its bass response in matters of weight and impact hasn't been goosed. Unlike Denon with their AH-D7000 and as also price would dictate, Sennheiser's target audience here aren't hip-hop freaks or reggae fanatics. This game is about linearity, resolution, speed and articulation, not ultimate bass power and crunch. For raw slammage, you'd be better off with a sealed design or Grado's PS-1000.

By the way, the 3D Mesh dust guard inserts are removable from beneath the circular ear cushions so they may be cleaned under warm running water whenever necessary. The photo shows one cover removed, driver assembly exposed underneath. The 3D mesh is very pliable and comes out very easy.

Now to performance. Break-in morphs in stages. The initial treble stridency is first to mellow but never fully falls in line with the rest. The bass fills out but as equal never truly meets up other sonic aspects which are of much higher caliber. A big culprit is the inferior 36-gauge stock cord. At least that's what Ken Ball's much superior 18-gauge ALO Audio replacement harness suggests. Jan Meier who'd sold me my HD800s and clearly loved his asked by e-mail what I thought. "I changed the wiring. Now I really like 'em" was my minimal reply. Herr Meier duly wired up his own 24-gauge harness. He was surprised but happily agreed on the improvements and now understood my initial reluctance. He said he'd next experiment with an 18-gauge leash such as I had even though Sennheiser's connectors provide very little room to cram the necessary conductive mass into. Ken Ball had already expressed much the same.

My point here isn't to promote one specific after-market replacement cord. My point is that Sennheiser's own leash is not up to snuff and hamstrings their terrific headphones from truly delivering their full potential, specifically overcoming remnants of treble brightness and edge and the disappointingly developed bass power and weight. All subsequent comments are with the ALO Audio harness in place.