The Sennheiser HD800s are power hungry headphones so you will most definitely need a good headphone amplifier in order to take full advantage of them, or close to. For this review I will be using a Head-Direct EF1, while it is not the most powerful amplifier out there it turned out to yield good synergy with the HD800s, as long as the tube used was a Sylvania 12AU7, with an RCA cleartop in the treble proved a bit too dominant. The source used was a HiFiMAN HM801 PMP, equipped with a PCM1704UK DAC from Burr-Brown. All sources files where either 96 kHz / 24 bit or 44.1 kHz / 16 bit FLAC files from HDTracks.com. The HiFiMAN HM801 was hooked up to the EF1 via a custom interconnect.
The first thing that hits you when you give the HD800s a listen is the resolution of which they reproduce music. Every single detail is painstakingly portrayed without any coloration. Everything just comes together with the HD800s - the bass, midrange, and treble all are beautifully balanced and almost without faults. I have been spending two weeks with the HD800 and have been using them intensively and went back and forth to them from my other cans and there is simply no comparison. The HD800s have a wider, deeper, truer sound stage than any set of headphones I have ever listened to. You get a great sense of space without it sounding like you are in the back of a theater, like with the AKG K701s. Even though the sound stage is expansive it is completely coherent, there are no odd gaps between left and right, up and down.
Further adding to the thrill of the listening to the HD800s is the speed and impact. These are the first headphones I have tried that reproduce the impact of drums and percussive qualities, of for instance acoustic guitars, spotless. It is a thrill to listen to because every hit sounds so lifelike and vibrant. Even in immensely complex passages in music the drivers manage to keep up and maintain all the original qualities.
The bass is there and the amount is perfect to my ear, not too much and not too little. If you are a basshead these will probably not do it for you, but for the rest of us the intensity is ideal. The bass is very present, well defined, and very fast and impactful. Extension is likewise really good.
Over the past weeks of intense use it has become clear to me that the HD800 is an all-around stellar performing headset, every single performance aspect is just so close to perfect. What amazes me the most is that Sennheiser have been able to push the envelope so much with these headphones. They are not a single step up from the HD580/600/650 headphones but in an entirely different league (both in terms of performance and price!), and the same applies in comparison to any of the headphones or in-ears for that matter I have tried or owned to date. What the HD800s lack is style, they feature plastic cups and albeit they are very comfy they just look too plain for such a luxury item price tag considered. Where the competitors like Denon, Ultrasone, are using lush materials for their top-of-the-line models these just look like a spaced out revision of an old headphone even though there is nothing old about the design of the HD800s.