This is the original flagship headphones by Sennheiser, HD 800 (S/N 49503). This is a super high quality, high fidelity headphones, designed for music and audio listening and enjoyment. I am the original owner. I purchased this unit a little while back. The unit is lightly used, it never left my home studio non smoking environment. I babied it, used it primarily for referencing and listening purposes. I have the original box, manual, and some of the packaging materials.

Delving into how this thing sounds, well there isn't much I can say that hasn't been already said before. This thing got raving positive reviews. The sound is super dynamic, wide, and vivid. It has a wide frequency response, and good bass extension but its not exactly a bass canon. You'll find listening to your music library and noticing details and soundstage you hadn't experienced before and will give you a new found appreciation for the sounds and music, Watching a movies or sound effects while gaming, is mind boggling good, the sonic image is remarkable.

The headphones are open back, meaning the sound will leak in and out of it, that's what gives it that airy open ended wide stereo image, so don't expect much in the way of noise isolation or cancellation.

The build quality is impeccable and the ergonomics are excellent. Even though these headphones are large they are light and I don't even feel them for hours on end. They don't clamp hard on your head either, its just nice, roomy and soft. 

These are rated at 300 Ohms, you can likely fare well with standard devices, but to fully experience these headphone's true capabilities you may benefit from pairing this up with a Amplifier/DAC.