If you love music or tend to listen to it a lot, then you're probably considering getting some high-end speakers at some point. The main problem with this is that we're currently living abroad, and buying something large bulky just doesn't work. We need something portable, so instead we're currently looking at high-end headphones. They are a lot cheaper, but you could still end up paying over $1,000.
If you live with other people, or have a partner, then you'll probably have used a pair of headphones to listen to music or watch a show. We've been doing this for years, and since most of our older headphones have broken (a pair of Sony MDR-V500DJ were just repaired), we're thinking about getting a pair of audiophile headphones. Most of these will necessitate a headphone amp, though some will work well without one. The cost of a pair of these is between $1,000 and $1,700, which is a lot less than when you check out some high end speakers. We've negated some of the higher priced options, such as the Ultrasone Edition 10, which cost $2,700 simply because they are too expensive for our budget.
There are currently two pairs of headphones that we are considering. Our purchase is still months away, and we've got lots of time to agonize over the slightest details and faults, but the Sennheiser HD 800 are currently at the top of our short list.
Sennheiser HD 800
These headphones aren't just for listening to music, but also watching media on your computer and home entertainment system. They reproduce the speaker-feel nicely, stopping you from feeling the "in ear" impression that most headphones give. The resulting sound is very clear and accurate. Unlike the Grado, the HD 800 will represent sound accurately. The Grados will make the music sound larger than life, which is good depending on what you do with them. While they are made out of plastic-like materials, they are comfortable and you'll be able to keep them on your ears for hours.
Grado PS 1000
Slightly more expensive than the HD 800, the Grado Professional Series 1000 sell for around $1,700, making them the most expensive pair in this post. Instead of using space-age materials, this pair opts for traditional materials and design. Initially, they were a lot more expensive, but they have come down in price significantly, making them a viable alternative to the HD 800. The sound in the low end is a bit sharper compared to the HD 800s. The bass goes pretty deep, thanks to an astonishing frequency range 5 to 50,000Hz. The separation of the sound also allows you to perceive individual instruments. They'll work on an MP3 player, but if you're getting these, it's best to pair them with a valve headphone amplifier.
Here are some more alternatives: the Denon AH-D7000, the Audio Technica ATH-W5000, the Beyerdynamic T1, and the Grado GS1000i.
MORE
Audiophile Headphones
Grado GR8 IEM Earbuds
10 Bargain Audiophile Products
(Images: Flickr member Noelas licensed for use under Creative Commons and Flickr member Noelas licensed for use under Creative Commons)

White Enamel Four-P...
Good luck in your quest! I'd suggest looking at the Audez'e LCD-2 headphones too. They seem to be getting very positive reviews although I've yet to hear them myself.
Anything that is over 200-300$ range is just a waste of money.
It just doesn't just justify the price.
I think Sennheiser HD 598 or similar headphones have perfect sound for 99% of people.
You can save all that cheddar and buy aiaiai tma-1 which has been put up head to head with the ath-m50 which was the renowned king of budget audio. Not only does the TMA-1 work well with out a eq but out performs most headphones with an eq and doesn't distort. Let alone it is probably the sexiest headset out there.
Get a pair of GK-Music Ultraphones. I'll buy you a hamburger if they don't sound as good if not better than any pair of the headphones listed above.
If you're truly in the market for a $1700 pair of headphones, you're not among the people who think the mid-range Sennheisers have perfect sound. I don't know why you need to convince someone they need to downgrade to a $300 dollar budget.
On the other hand, a post on ~$300 hifi headphones would have been more interesting and useful for 99% of readers. There are some interesting discussions to be had in that space, as well as some obscure giant killers.
I think anyone in the $1700 market is wasting their money. There are plenty of $300 headphones that are going to sound just as good for sure. Any benefit gained by an extra $900 spent (seriously, like zero gain) will not be worth the cost ever. That $900 goes to extra money in the company's pocket and some more expensive materials in the construction of the headphones, but certainly not in the quality of the audio.