Pros: Massive soundstage. Very high-resolution sound with low resonance. Very comfortable. Quality construction.
Cons: Not natural sounding; the tonality is bright with a lack of proper body and weight to the sound. Paint job fragile. Overpriced.
I purchased this headphone for full retail price a couple of years ago, and in the beginning, I felt very positive about it. But things change, and as I got to try many other high end offering by other manufacturers, as I got to try this headphone with different amps, sources, cables and so forth, I have come to the conclusion that this headphone is perhaps the most overhyped piece of audio gear in the head-fi industry. The truth hurts, but you learn from your mistakes.
As controversial as it may be, I felt the need to change my positive review and write what I feel about the HD 800s.
To start with the positive, build quality and ergonomics here are great. This is a very cool-looking, precisely designed headphone that makes a luxurious impression, especially when resting in the storage box. The headband adjustment mechanism feels very well constructed. The earpad/headband material attracts dirt and dust like crazy, but feels great to the touch and is very comfortable against the skin for extended listening sessions. The plastic doesn't feel as great as the aluminum on the STAX SR-009, but is really solid nonetheless. I'm a bit sceptical about the paint job though; the finish is fragile and will tear if you don't treat the headphone carefully.
The cable is very well made; thick, non-microphonic, with a really hefty, quality 6,3mm plug at the end.
Comfort is absolutely first rate. The headphone is a bit on the heavy side and after several hours, the headband starts to feel uncomfortable on top of my head, but that may just be me. The earcup pressure is just perfect and the headphone almost feels like it disappears from your head after a while. The large space inside the earcups coupled with the open design makes sure you never get hot or annoyed wearing them.
So far, everything is good.
Sound wise, this is a very clean sounding headphone. Sennheiser did a great job designing a headphone with minimal resonance factor and muffling of the audio. As a result, the HD 800 is very resolving and therefore picky about the source gear, and especially recording quality. Lesser recordings simply will not do this headphone justice. Of course, this resolving sound signature will allow for very crisp detail.
Those large, angled ring-drivers also provide a very large soundstage, with great sense of depth and layering. Room acoustics come through very naturally and the headphone is very good at separating dense, orchestral music.
BUT, the tonality just isn't realistic. The overall signature is a bit bright - especially in the 6khz area - which gives the impression of more details, but becomes tiresome to listen to after a while. Cymbals sound to splashy, violins sound to shiny, sibilant sounds are over-accentuated - things just *don't sound like real life*. (Granted, like most Sennheiser headphones the HD 800 is laid-back and quite smooth sounding, so it's not biting or piercing the way Ultrasone and Grado headphones tend to be.)
The same goes with the bass. I find the bass very tightly controlled, but neither well extended nor impactful. There isn't enough punch and weight to it, and there's not much warmth either. Drums sound pathetically weak for a headphone priced at $1500 and the midrange suffers from this lack of body.
Just try to listen to a live jazz band performing, and then go listen to the HD 800. It doesn't sound AT ALL alike. The string bass sounds present, full and thick in real life. It sounds thin and lifeless on the HD 800.
The midrange could've been so good if the frequency extremes were more natural, because the openness of the HD 800 really allows for a very airy, clear midrange. But instead, things sound dry. Even with great recordings, there's always a certain degree of thinness and brightness to the music, with some grain and sharpness to the upper midrange. You hear the guitar very clearly, with excellent crispness, but the sound of the box of the guitar is subdued. Female vocals, a particular weakness of mine, sound a bit articifical, if only slight. But at this price, "slight" turns to "significant".
With a Cardas cable, the sound gains a bit more body and slightly less glare to the treble, which is a good thing. But it still doesn't make the headphone entirely neutral, and let's face it; why in the name of god should you have to buy an aftermarket cable for hundreds of dollars to get the sound right with your $1500 high-end, flagship headphone from a large company like Sennheiser?
There is a lot of talk around the forums that the HD 800 really needs a great tube amp to sound it's best. And that's true. I've heard the HD 800 with the Leben CS300 and while the combo didn't win me over, it sounded very good. Much more body and no treble glare left to speak of. But my opinion is this: if you have to use a tube amp to *change* the sound of the headphone in order to make it sound good, then that ruins the idea a bit. A tube amp like the Leben colors the sound; it adds distortion, makes things different than what's originally intended. This goes against my idea of high-end hifi: a clean path through the entire audio chain. I think the source chain should be as neutral and as transparent as possible with minimal distortion, in order to make the headphones themselves shine through fully and display their respective strengths. This is the proper way of judging the sound of a headphone, isn't it?
If you have two really expensive cars, you should use a track that's optimal for them to achieve high performance. If both cars have their different weaknesses, no modifications should be enabled to each, and no changes should be made to the track to cover up those weaknesses. That would be cheating!
And that goes here as well, it's just that instead of two cars you have two different sounding headphones and instead of track you have your source chain. This is, of course, my opinion only. But I hope it's a reasonable explanation to why I don't think a tube amp should be used to judge a headphone. I feel you should judge the original, intended sound of the headphone.
And driven from a neutral system, the HD 800 fails to impress. My positive impression of it has gone colder and colder, and I have now sold it. The sad truth is that not only do I prefer pretty much every STAX headphone made, the Audeze LCD-2 and the Beyerdynamic T1 to the HD 800 - I even prefer many cheaper headphones to the HD 800, like Sennheiser's own HD600, HD650 and even the portable momentum, which is a fantastic sounding headphone and my only headphone at this time. No, the Momentum, HD 600, HD 650 and even the LCD-2 don't have the openness and crispness of the HD 800, but they are all more neutral, easier on the ears and more fun to listen to. The HD 800 just comes down dull and clinical compared to most.
It's a shame, but it's what I honestly feel. And no matter how many people who will hate me for saying it, I think the HD 800 is a failed, if ambitious, achievement by Sennheiser. The HD 700 made the sound fuller and warmer, but instead made the treble even brighter end quite edgy, so that one wasn't right either. If you want the best from Sennheiser, the HD 600/650 with a replacement cable and a great system is what you want.
If you want better options at this price, the Beyerdynamic T1, LCD-2 and the cheaper STAX offerings are recommended.