Hi,
I am new to Tech Enclave, however music has long been a passion to me. Lets start on the onset asking the rudiment question? What is a Gaming Headphone? or In this case, what did dragon hunter actually want:
a. The Budget is < 6K.
b. A Comfort level with the headphones which perhaps enables him to sit long on his gaming platform.
He of course didnt ask for the following however I would like to add them as well:
c. Good SQ, which makes him feel part of the arena.
I would also touch upon the misnomer of 5.1 Headphones (however not dwell upon it in detail).
As cartel of manufactures, one would always like to push new technology even though there may not be an actual market. The reason being most of the company policy are governed by sales (revenue). Lets talk about 5.1 first, the .1 in 5.1 denotes the channel of Sub-woofer, so if your transducers are capable of producing the frequencies of the sub, you will not need the sub. Now lets involve a little bit of physics here. Phase shift, channel and amplitude are used to move the sound. Our ears are capable of hearing the phase difference, time difference and the change of amplitude (all essential to make a positional audio). Similarly passing the same information to both the channel kills the position and the sound assumes to be coming from the "Center" or "Straight". A permutation and combination would generate other channel: aft left and aft right, rear left and rear right etc. Low frequency doesnt have the sense of direction (due diffraction) that is the reason you have only one sub-woofer in most of the home-theater systems for two ears!
However, this will not stop manufactures from increasing their revenue by making 5.1 or 7.1 even 9.1 headphones!
Lets move on now "b".
What are factors that govern "comfort" in a headphone.
a. Weight: or more important the distribution of weight. We all understand how the moment work in an Inertia.
b. Pressure Point: this according to me is the most important aspect that governs wearing comfort. let me break it down further(which can be further be sub-subdivided).
i. how is perpendicular weight distributed over the head
ii. how does your cups generate pressure over your ears
iii. How much area would the cup engulf to have pressure exerted over your ears or the area surrounding it.
iv. the direction of the force surrounding the cups.
c. Material used at these "Pressure Points": Fabric (cotton), leather, chemise, plastic, suede, nylon and other synthetic material. Of late lot of manufactures also use memory-foam, which has better pressure distribution. The cushion material is equally important. All of them have there own pros and cons. The chassis similarly are made of metals, alloys, carbon composites, plastic or a combination thereof, an important aspect of them being how much memory do they retain over a period of time.
Now Lets dwell upon d., 'the sound quality'. Since this topic in itself is very exhaustive, so instead lets ask the question: Why is sound quality important?

Because if the sound is not good you will not feel like wearing the headphones ...
I will also dwell upon bass here since some of the members touched upon it. If the drivers have the capability of producing the base without distortion, it shouldn't matter how bass-heavy the headphone is. Why? That is because, an user can always fine-tune the environment, codecs and equalizers to alter the sound to suit his or her taste.
Sound isolation or listening environment is another factor that you may like to consider in an gaming headphone.
So finally lets get to the point a. How may headphones gives you all of above at sub 6K? None!
Also let me now give a reply to some of the headphones talked about in the thread so far:
Senn HD 238: Its on the ear, I would recommend over the ear for better pressure distribution and comfort. Its a fair portable headphone though. Not recommended for desktop users.
Audio-Technica ATH-M50: Very good sound quality and sound isolation. However the headphone sits very tight over your head and ears to offer a better sound isolation. Also its above 6K.
Audio-Technica ATH-AD 700. Good in all the above aspect. Sub 6k, bass is a tad bit thin. Has very good sense of space. However is an open air dynamic can, so it can be loud. If you plan to sit next to your wife and play the games, it can be noisy. Recommended.
Sure Headphones: I have not heard them lately, however they have not been known to be very popular with the gaming mass. My exposure to them have been mainly on the IEMs. Sure is more known for its Pro Audio products.
I would also like you to try out the ATH-AD500 and ATH-AD300. The comparison weight for a similar chassis is
AD700/500/300 is 280gms/260gms/250gms. Driver size 53mm/53mm/40mm, output sound(per mili watt) 98db/99db/96db
impedence(in ohms) 32/66/32.
I hope it helps.
I own all the above headphones personally.
Disclaimer: We are the Country Distributor for Audio Technica.