((This post will constantly be in a work in progress, the headphone world is constantly changing with new competitors and my goal is to keep this up to date with as much detail as possible. This will be no easy goal and I'm asking your help to correct any information, or add any as needed! A PM will yield best results when looking to change anything here.
Before reading this thread I want everyone to realize that sound is subjective. Something that one person may find to be a great headphone may in-fact sound terrible to the next person. With that said I'd like to keep the discussion of headphones civilized. I realize opinions can cause someone to get heated possibly, but we're all here for the same purpose! That being the most important thing to note, there are other important things to consider when buying a new set of headphones and this information will be highly helpful to provide when asking for advice:
1: Location: Where do you intend on using these? If you're looking for a portable solution, a pair of open full sized circumaural headphones may not be for you. Consider the most practical option, not the flashiest.
2: Budget: A budget is very important to set-up before you consider your purchase. Some headphones are known to "need" amps to shine. The headphones will still work without an amp, but some headphones won't be up to their potential without one.
3: Music: The type of music you listen to will be very important when looking for a new pair of headphones. If you like bass heavy music then you're going to want something that has some bass impact.
Before I get into the guide I would like to give a quick explanation of the types of headphones.
IEMs: Otherwise known as in-ear monitors. These are headphones that go into your ear similar to ear buds, but they go a step further by nesting into your ear canal. They generally provide a higher level of isolation than earbuds
Earbuds: These are the headphones that you'll see come with an iPod. They sit in the outside of the ear, and don't provide much isolation. These aren't very popular in the audiophile world and generally you won't find many higher end ones.
Full-Sized, Circumaural: These can be open or closed headphones, it doesn't matter. The defining characteristic of these is that they will completely cover your ear inside the pad. The pad of the headphone generally won't touch the ear, rather make a seal around the outside of the ear. These headphones tend to be large and are generally not ideal for portable use.
Full-Sized, Supra-aural: These can be open or closed headphones, it doesn't matter. The defining characteristic of these is that they sit on the ear, rather than cover your ear.
Head-Fi - Many of you may already know about this site, overall it's fantastic. Be weary of audiophoolery though, a lot of people tend to get caught up in searching for the perfect sound and lose sight of what's important, the music.
Multi IEM Review - A very nice guide to many IEMs in many price brackets with more added regularly.
Beyerdynamic Reference Chart - This is an amazingly useful post on the varieties of the Beyerdynamic Dt770, 880, and 990, models that any user considering these models should purchase.
Portable Headphone Shootout - This is an incredibly useful guide for headphones on the go for multiple price brackets and many headphones with more added regularly.
MLE's Gaming Guide - An excellent guide to gaming headsets.
Anything But iPod - Features information and reviews on not just headphones but other audio equipment with some trusted reviews.
HeadRoom - A nice site with some fantastic resources. Headphones tend to be a bit overpriced here though.
InnerFidelity - Great unbiased reviews.
When considering your headphone purchase it's always best to attempt to find a place to demo them yourself to try your own music on them and see if they suit your ears. Remember sound is subjective and one headphone I enjoy the next person may not. This is meant to help guide you into the more popular and well received models available to further research.
Things to avoid:
In general it's best to avoid products made by Skullcandy, Bose, Beats, or Monster unless otherwise specified in this thread. These companies spend a lot of money on advertising and looks rather than quality. That isn't to say these companies haven't put out headphones worth buying, the Monster Turbine Coppers are actually fantastic IEMs, it's just that a lot of the time you're paying a premium for the name.
Active Noise Canceling is also something else you'll want to avoid. In-general the average person will get the isolation needed from IEMs or other full-sized headphones. With active noise canceling you're going to pay a premium on the noise canceling tech, rather than the sound quality. Only buy these, or even consider them, if you absolutely need them.
(1) Denotes amp is not required and the headphone will probably not see any change with one.
(2) Denotes amp is not required, but one is recommended.
(3) Denotes amp is required. Using these without an amp will leave much to be desired.
Any headphone with a B next to the number, IE:
(2-B) indicates that it's a bass heavy headphone.
Any headphone with an S next to the number, IE:
(2-S) indicates that they are made for studio monitoring, though may also be good for listening.
Budget Headphones: $0-$75
Looking for a pair of headphones for travel, something cheap to throw around? Or perhaps you can't justify spending much on a pair of headphones but want something of decent value? Look here!
Entry Level Headphones: $75-$150
These headphones are for people who want to take the next step up and possibly enter the audiophile world. The low price-tag does not mean these headphones aren't serious about sound!
Entry Level Headphones
Mid-Range Headphones: $150-$300
Don't let the title fool you, these headphones are serious about their sound quality and many users will be completely satisfied stopping here in their quest for their sound. Perhaps you're looking to upgrade, sidegrade, or enter the grade at all, these are excellent headphones that will satisfy most.
Upper Mid-Range Headphones: $300-$500
You've perhaps have gotten a taste of some other headphones and wanted to see what the upper tiers are like, or you're a risk taker and are spending "big" on your first pair. Either way these are part of the upper echelon of headphones and are highly regarded for their sound quality.
Upper Mid-Range Headphones
Audiophile Headphones: $500+
These headphones are the end of the line, the cream of the crop, the absolute "best" available. Chances are if you've moved on to a headphone in this price range you already know what you want, but here's some of the top picks!
These headphones are all pretty much unobtainable, even if you do have the money, due to the extreme rarity of them. You can look, but you can't touch.
For all the miscellaneous items that go with headphones.
[align=center]Headphone, Amp, & DAC Registry
Things to do:
-Complete the list of headphones, yes it will be huge, but it will be comprehensive and give users a multitude of ideas for their headphone purchase.
-Add a list of Amps and DACs and Accessories.
-Desktop and Portable sections.
-Amp, Amp/DAC, DAC
I stole this from another site, but I will try to update this as much as I can.