Pros: Perhaps the world's most transparent headphone. Incredible details, extension and precision. Unmatched spacial presentation.
Cons: Extremely sensitive to what's down the line, requires meticulous setup. Hopeless to demo, needs extensive listening to judge.
I've owned the HD800's for the better part of two years, by now I have hundreds and hundreds of hours of listening time behind me. It is never easy to review a flagship product but the HD800 is harder still, it is not a random thing that I've held off doing this review for so long.
The first time I demoed the HD800 I was of course incredibly exited to try Sennheiser latest and greatest headphone, who wouldn't be? I was impressed by the build quality, the "all-day-long-disappear-on-your-head" comfort, the attention to detail, the very German "rightness" of it all. As I listened to some of my favorite demo tracks in the hi-fi store I was amazed by the details, spacial presentation and precision. But at the end of it all I also came away more than a little perplexed, and there was no instant buy that day. Some of my favorite recordings had sounded a bit dry, hollow and sterile. Almost as if they had been stripped of emotion.
So at the time I simply concluded that the HD800 was competent, but that it wasn't for me. And no great loss since I carried on with my HD650's, a pair of headphones which I to this day still hold in very high regard.
But after a year or so I started thinking about the HD800's again, I guess curiosity is the only way I can describe it. Was I sure there really wasn't anything special with the HD800? This was Sennheiser we were talking about, could Sennheiser really be wrong? So I started reading about the HD800's, and how divided the opinions on them were. This didn't seem to be a "normal" pair of headphones which you could just demo for an hour or so. These headphones required you to actually buy them, install them in your system, set them up the way you want them, let the headphones break in and then let your ears acclimatize themselves.
But even armed with this knowledge I still wasn't completely sold on buying them, it's a lot of money to put down on the table when you're not sure if you're going to like something or not. But one day I spotted a mint second hand pair from a professional reseller at a price that was just too good to pass on. So I decided just to go for it - "heck for that price I can probably sell them for the same again if I don't like them" I said to myself.
And away from the pressure of the demo room I slowly began to warm to the HD800's and appreciate what's so special about them. This isn't really a headphone that's built to be a headphone, this is a set of headphones that's supposed to sound like a pair of speakers standing in front of you.
I have never before or since had a pair of headphones that image so well, it is simply uncanny and something that has to be experienced. Since they are so transparent they also respond extremely well to tweaking. If you change a cable, change the source or give them a +2 dB bass boost you can really hear the difference. This is both good and bad; it is good because they respond very well to changes down the line. It is bad because they are extremely demanding; if you have unclean power in your home, a low quality DAC, a humming amp or a low quality recording you will hear it.
And in this regard the HD800's are extremely unflattering, they will show absolutely no mercy towards bad recordings. On the other hand; if you give them top-notch components and a good recording they will blow almost everything else out of the water. This is why I like to think of the HD800's as a highly strung F1 car. They can be a pair of demanding son-of-a-somethings, but if you get them set up right... boy do they perform.
As such I highly recommend the HD800's, I've derived tons of listening pleasure from mine. It is a headphone that I like to think can do things which no other headphone can. But it is also a headphone that's best purchased when you've already owned a couple of other headphones, and you already have a very competent DAC and AMP setup. Even then it might not be a pair of headphones that you want to use all the time, or for all your recordings. But with the right setup, and the right recordings, you can experience "moments of greatness" which few other headphones can match.