AKG K812 - Reviews
Pros: Fabulous sound, solid controlled bass, lovely midrange and treble
Cons: None
I fully understand that everyone who has listened to the K812's is entitled to their own sweet opinion but the hoo ha concerning these headphones only created uncertainty in my mind and I stupidly allowed myself to be swayed unduly by other people's opinions. I tried to get hold of a dem pair of K812's in the UK but sadly AKG UK had decided to place the sale of the K812's in the hands of a company who didn't believe in customer service and none of the sellers appointed by this company had a dem pair. Understandbly, the sellers informed me that they could not afford to stock a pair of headphones at this price range for dem purposes. Basically, AKG UK has gone about the marketing & selling of K812's in the wrong way and instead of getting that the real market for the K812's was in the very healthy audiophile marketplace, they have promoted these wonderful headphones to the "professional" customer (I wonder how many of this customer actually spent £1,000 on a pair of headphones for their work purposes?). I even tried to persuade the distributors to supply the Hi Fi Lounge hi fi dealership who have a dedicated headphone building but this wasn't allowed.
Sorry, I am expressing my frustration rather than telling anyone about my experience with the K812. I own, as so many do on head-fi, a number of headphones including HD600's (too slipper like for me), Grado RS2i (hell, I can't remember what they sound like, time I sold them perhaps), AKG K550's (great value, bought because I needed a pair of closed), AKG K702/65's (bought when the K812's first came out and I thought the K812's  were too expensive, stupid me).
So I really like the AKG general house sound as I guess others like another headphone manufacturer's house sound? Anyway, although I was really enjoying my K702/65's I was aware of some shortcomings, I wanted more treble, more detail, a better quality bass so I thought I would ignore the "varied" reviews and I bought the K812's from Amazon thereby ensuring the UK distributor's sellers did not get the sale, a lack of co-operation cuts both ways chaps.
I love these headphones, absolutely fabulous sound (for me). I love the solid & extended bass, the spaciousness, the additional treble over the K702/65's, the lovely midrange. I generally listen to headphones with my Cowan Plenue 1 & Colorfly C4 Pro DAP's and the K812's are easier to drive than the K702/65's so this is a really useful aspect. One review I read talked about the K812's being compatible with iPhones etc on their own but who would drive a pair of top notch headphones in this way? But it is great that the K812's do not challenge my DAP's and the arrival of the K812's prompted me to buy an Audioquest Dragonfly v.2 and the combination is a great match.
The K812 is well made, like the mix of materials, not too heavy & comfortable for extended listening but I would have loved a 3ft cable as well as the 10ft one. Personally I have no use for a 10ft cable.
Have ordered a 3ft cable from Double Helix Cables but still have 2 months to go before it arrives, can't wait......
Now before everyone thinks I'm just an AKG fanboy, I want to say I'm in the 50-60 age range and it could well be that much younger ears would result in a different review. This is my review however and my best advice is to grab a well run in pair if you can and otherwise just buy the K812's like I wish I had done.
I PAID £938 IN THE UK, have converted this to USD 1400.
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Pros: Top-Tier Reference Sound Quality, Top-Notch Build Quality, Excellent Comfort
Cons: Slightly Heavy

Me: I am a 21 year old student living in a small town in India. I would like to call myself a music enthusiast, rather than an audiophile. I was inspired by music since childhood, and as the time passed, the passion of music grew in me, and that subsequently led me to join Head-Fi. Eventually, I found the pleasure of listening to music mainly by the HD600 and recently, by the seductive LCD2 headphones, and realized the true components of recorded music. I usually like to listen to Indian Classical Music along with Bollywood songs. My main listening genres include classical, vocal, instrumental, jazz and sometimes pop.  With time, my sonic preferences have very much grown. I avidly admire transparency, accuracy along with neutrality, & this has led me to review the AKG’s prestigious K812 flagship headphones.

Intro:  AKG Acoustics (Akustische und Kino-Geräte G.m.b.H) is well recognized, established & one of the oldest audio brand specializing in the area of audio & headphones. They are headquartered in Vienna, Austria.  The ‘K’ series line is a very popular and long running headphone offering from AKG. They have a specific vision in making their products: Their products should last long and should employ quality engineering for precise and accurate sound reproduction, with state of art cutting edge technology. All the headphones are designed by their engineers in Austria. Few headphones are manufactured in China. The K812 headphones the flagship & best headphones AKG can offer today. K812 replaced K712 as flagship headphones in the year of 2013. These are studio reference headphones. The pair I will reviewing belongs to latest batch & current year manufacturing. The K812 is completely manufactured in Slovakia.
Founded in 1947 by Dr. Rudolf Görike & Ernst Pless. Originally, their main aim was to provide technical equipment for cinemas: loudspeakers, film projectors and light meters. Their business slowly expanded and AKG started selling car horns, door intercoms, carbon capsules for telephones, headsets and cushion speakers. The first AKG microphone was used by radio stations & Theaters. AKG developed its first patents, the moving coil technology and the principle of mass load membranes, allowing its products to have extended frequency ranges.
With the creation of the D12 microphone in 1953, AKG achieved international fame, setting the standard for voice transmissions. Being the world's first dynamic cardioid microphone, it possessed excellent sonic qualities for that time, making its way into radio stations and recording studios from across the world. In 1994, AKG was acquired by Harman International Industries, and they later setup AKG USA’s headquarters in California.
In 2010, AKG Acoustics received a Grammy Award for the work the company has done in the recording field.
Specifications of K812:
Headphone type
Audio Frequency bandwidth
5 to 54000 Hz
Sensitivity headphones
110 dB SPL/V
Max. Input Power
300 mW
Rated Impedance
36 Ohms
Detachable cable
Cable Length
3 m
Earpads Replaceable
Audio Interface
Screw-on Jack Combo (1/4" and 1/8")
Interface Finish
Dimensions / Weight
Net Weight
390 g

Let us see what the K812 has got for us,
Packaging and Accessories: The K812’s arrive packed inside a very premium and heavy black cardboard box. The box has a magnetic lock. Once the box is flipped open, The K812 is seen resting on the Sieveking headphone stand, which provided by AKG in the box. Nothing fancy, basic accessories included. But each and every part has a premium quality and feel to it.
List of accessories in the box, which include the following:
Headphone Cable: About 2.5 meters long, terminating in 3.5mm.
Headphone Stand: Excellent quality universal headphone stand to display headphones when not in use.
¼” Screw on Converter: To plug in the K812 in the 6.5mm headphone jacks.
User Manual: Contains instructions to operate the K812 and other warranty information.

Design and Build: AKG’s K812 has a top notch build quality. It employs metal constructions in most of the areas. AKG K812 headphones use suspended headband which can be manually adjusted for precise fit, which ensures in least possible physical pressure on head. The headband has a foam-pleather base with ventilation vents, & is very accurately angled. It is attached to the main headphone frame which holds the headphone together.
The K812 has an extremely sophisticated build with high technology materials & latest scientific designs. The manual adjustment of headband distance can be adjusted by pushing he button and sliding gently as desired. The K812 is designed in such a remarkable manner, that clamping force is almost zero. This is the first time I have ever come across a headphone (along with Sennheiser HD800) which offers such luxurious design & engineering elements.
The K812 is a fully open headphone, hence has vents for air intake at either side of headphone. Driver shell rotates about its own axis to fit various types of human skulls. The whole headphone is supported on by the two parallel outer headband beams, which are flexible and adopting. These also carry wiring for opposite driver (right). The K812 carries all-new and latest generation top notch performance drivers developed by engineers at AKG specifically for K812 alone. This driver carries an extremely powerful 1.5 Tesla magnetic field capable magnet. The diameter is 53mm, one of the largest drivers ever made. The sound waves coming towards out of drivers are treated to ‘air’ by open mesh, allowing air to blend with sound waves for a very airy presentation. 
Cable has a very good build. It is straight, flexible and does not get tangled. I could not notice the presence of any microphonics. Plug is straight and gold plated. The stock cable does a great job in transferring signals along with great transparency. The cable on headphone has three pins, and is configured for single end termination; balanced mode mode is not supported. Please note: While inserting cable plug into K812’s socket, carefully align to the indicating red line and gently push in. To remove the cable, gently pull out.

Comfort:  K812’s are excellently comfortable to wear, even for longer sessions. These feel really wll designed as per human analogy. Clamp force is almost non existent, and ears have been given an excellent space to reside, do not touch anywhere. The earpads are made up of leather, are high quality ones. The Space inside the earpads is also great, great amount of depth and space.  The earpads on K812 are designed such that, the area of contact around the ears or anywhere is made as less as possible, and clamp force is reduced to almost zero: This will result in an excellent comfort.
These ear pads are very soft & flexible in nature, which ensures in better comfort & adoption without compromising consistency, and also in durability of the pads themselves. The earpads can be removed to clean or replace with a simple anti-clockwise horizontal twist. These earpads are called as “Sound Sealer” by AKG. Hence, K812 ‘s  earpads seal out & engulf the user’s ears, rather than sitting around the ears. Single downside in this department weight, as the K812 weighs slightly on heavy side with 390 grams (owing to its solid build) feels slightly heavy on worn on. But again the excellent design factor makes up for it.
Overall, The K812’s are one of the worlds most well designed and most comfortable headphones.

Sound:  The K812 has a vastly neutral “mesmerizing” sonic character. ‘Accuracy, Transparency, Details’ are the key terms.  Emphasis is not given at any particular frequency range; all ranges are completely flat, making these truly spectacular reference headphones.
Burn in: These perform consistently, and I could not observe any major sonic change with burn in. I have heard these from right out of the box till few hundred hours.
Lows: are very accurate, tight and refined; has a strong impact. Depth is excellent, the lows go very deep with authority. They also have an appreciable amount of body & quantity
Mids: Neutral, very detailed & transparent.  Special mention is about the naturalness and tonality. The mids of K812 are very neutral, but are presented in an extremely silky manner.
Highs: Very are clear, extended, airy & detailed. Very transparent & sensitive as per the given setup & recording.
Soundstage: The K812’s soundstage is breathtakingly airy, spacious, and fully circular 3D life like soundstage. Imaging is again spatial, with instruments placements very accurately positioned. Component/instruments are clearly and vividly separated and explained in a very detailed manner. According to my observation, these headphones are very neutral, and accurately represent the given recording. Given its transparent nature, I can say the K812’s are strictly not forgiving to poor recordings. Hence these are transparent, revealing and resolving.

Comparison: Let us take a brief look at other popular top notch & excellent performing headphones available in similar price point.
I would like to compare the AKG’s“mesmerizing” K812 to Sennheiser’s “mighty” HD800 & Audeze’s “passionate” LCD-2F. All these three headphones are open backs, over ear. They are also very neutral by sonic response, but presented in different fashions. These are all top notch headphones and one of the world’s finest.
Sennheiser HD800: A Solid performer and a well established headphone, which is sonically extremely good performing. Sonically it is vastly neutral with no emphasis on any frequency range. But highs are very sensitive to the setup & recording used.  HD800 definitely feels (and indeed is) Lighter than K812 by weight. The HD800 is also slightly more comfortable owing its design & comfort principles that is compatible with majority of users. After intensive listening, I could observe K812 was comparatively ahead in performance in the following departments: In rest of the aspects, HD800 is marginally superior.
Lows: The K812 audibly has a deeper Lows with more authority without compromising its neutrality. Accuracy, detailing is same on both headphones.
Tonality: The K812 delivers a very realistic tonality which feels very silky & is simply mesmerizing when compared to HD800, which has a relatively vast flat mids.
Soundstage depth & layering: This where HD800 is left behind by K812. The overall depth across depth offered in K812 is simply amazing & spectacular, the stage goes very deep. But when the matter comes to width & height, HD800 performs better.
Amping: HD800 is very sensitive when it comes to headphone amplifiers, and it promptly points out the different between various amps in a accurate fashion. Whereas the K812 is comparatively more steady and accommodating to amps, so it ‘goes along’ with amps without much fuss.  Also the K812 is much more efficient & easier drive when related to HD800.
Summary: Both are extremely good performing headphones, and differ by final presentation delivered. Considering overall sonic traits, AKG’s K812 will sound slightly more ‘musical & enjoyable’ but without compromising its technical or reference deliverance aspect. Technically, HD800 is a more suitable headphone for critical listening and mastering purposes. But the K812 is more versatile & stable, proving to be great with mastering as well as music listening.
Both HD800 & K812 are top-notch reference class headphones & perform amazingly.
Audeze LCD-2F: Without a second thought, it offers the most accurate, linear & deepest lows of all headphones in sub 1000$. Mids are presented in a beautiful manner with ‘thickness’ and has a lovable realistic tonality. Highs although accurate, do not have enough details. Soundstage is very good and circular, but nowhere near the capabilities of HD800 & K812. Therefore the LCD-2F is not technically superior when compared to HD800 & K812. LCD-2’s strength elsewhere: In music listening. HD800 & K812 are reference level headphones whereas the LCD-2 is a headphone designed and aimed primarily for music listening.
The LCD-2 is one of the heaviest headphones (by physical weight), and this makes the LCD-2 to make a compromise in comfort department.  Although , the LCD-2’s already have a very good comfort & ergonomics (when weight factor is excluded). The strong point for LCD-2 will be primarily music listening, LCD-2 presents itself in a complete opposite fashion than that of HD800 & K812. Hence, it is safe to say, if HD800 & K812 are on one bank of river, then the LCD-2 is on the other one. They are completely opposite& never meet.
The HD800 & K812 are superior reference level headphones whereas the LCD-2 is a headphone designed and aimed primarily for music listening.

Amplification: These K812’s are rated at 36 ohms and are indeed designed to be power efficient, can be run comfortably by DAP’s. But since these are top tier reference headphones, the K812’s scale really well with setups, and an well performing amp/dac is strongly recommended for optimal performance delivery. The K812 very much appreciates amplifiers which are revealing or transparent with powerful current output. Ideal amp/dac with a good match/performance for K812 include: Objective2/Odac & Schiit Magni/Modi Stack, amongst few others. These devices are very much affordable and are easily available.

Conclusion:  The K812 headphones are phenomenal performing headphones. It is one of the few amazingly performing top tier reference headphones. The K812 is the flagship headphones from AKG, and the K812 is the absolute best which a renowned brand like AKG can offer. The K812’s deliver a breathtaking sonic performance. These deliver exactly what is fed into them, thus making the K812’s a technically ideal & extremely transparent headphones. Absolutely Mesmerizing & Marvelous pair of superior reference headphones by AKG.
Top-Tier Reference Sound quality: “Mesmerizing” Sound presentation here is vastly neutral, with excellent response from across frequency band, and is very much helpful for critical listening as well as for casual musical pleasure.  K812 is very responsive, with great speed. With sheer amount of transparency & speed, the K812’s are simply one of the best top-tier performance headphones one can access get today. It performs extremely well and is neck-to-neck with HD800 by performance.
Top notch Build Quality: AKG K812 is very well engineered and designed. It is the showcase of AKG’s engineering. It is wisely built, by using cutting edge technology materials which provide a very durable life for the headphones. These are made in Slovakia with individual attention to each unit.
Excellent Comfort: Owing to their scientific & ergonomic design, including near zero clamping force & engulfing earpads, the K812’s feel very welcoming & comfortable.
Value: AKG K812 puts up an extremely good performance and it is definitely worthy for its offering price. This makes K812 a fantastic purchase for professionals & enthusiasts alike.
Weight: The K812 weighs 390 grams, which is slightly on the weightier side. But this factor is mostly not noticed while worn, and is very much comfortable owing to its well implemented & ergonomic design.


@Brooko - So perhaps the uneven treble explains the Sennheiser HD555 level audio quality rating. Alot of these high end headphones seem to suffer with treble issues.
Yep - depends on your sensitivity to it.  I personally liked the AKG K812, and also really enjoyed the HD800 and my own T1.  Mind you I also loved the DT880 and Grado 325i - so I'm a bad one to ask about treble sensitivity :wink:
Aside from the treble - the one thing I couldn't understand with the K812 was the cable.  It just doesn't gel with the rest fo the headphone.  Yes it works. But it feels cheap, thin, is prone to tangle - I hated it.  I'm still on the fence about getting a K812 - they're severely overpriced at anywhere over 1K if you ask me.  If I do eventually gte one though - the first thing that's getting replaced is that awful cable.
iPhone Awesome
iPhone Awesome
A fair review. Therefore I still have to watch a chance where I can directly compare HD800 with this.... In the meantime get the money ready.
Pros: Organic, realistic, detailed and excellent imaging
Cons: Unforgiving of weakness in chain
I have owned the AKG K702 for a few years now. Of course, it is one of the most difficult to drive full sized cans around. If not properly driven, it sounds rather bright and is bass light. Feed it enough power, the sound you get out of it is rich and there some serious bass there. The K702 was under appreciated by the general public but a jealously guarded little secret of audiophiles who knew its true nature. It was also many years since AKG first came out with the K702 as its flagship headphone. 
We all despaired if AKG would ever rise to such heights again. Of course, AKG surprised us a few years back with the AKG K3003 which was a phenomenal little in ear monitor, with a soundstage like it thought it was a pair of full sized cans.
As to how I came upon the AKG K812, I have two good audiophile friends in Singapore to thank: Joe and Ken. When the AKG K812 was showcased in Singapore last December during Mook, I was laid up in bed because of a bad bout of flu. Immediately after that, I travelled to NYC for a few weeks. Hence, I did not hear about the buzz the K812 caused during Mook. However, separately, both of them swore blind that they thought it was the best dynamic in the market and that I would love it. Perhaps I should explain - the both of them almost NEVER agree on any iem or can. This had to be a first. I knew it was a sign... So, when limited stock arrived at Jaben, I made sure that I had one. Wilson and Claire were kind enough to set one aside for me. 
As a background, I have practically all the TOTL headphones: LCD 2 & 3, HD800, Beyerdynamic T1, Hifiman HE-6, HE-5LE, HE-500, Fostex TH900, plus all the higher end Grados (save for the PS1000) and the Abyss. 
Build Quality
The build quality of the AKG K812 is good. There is a nice hefty solid feel about them. It doesn't feel too heavy, certainly nothing close to the Audezes. I particularly liked the ear pads which was oh so comfortable and my ears fit nicely within.
The only downside is that the cable connection is similar to the old AKGs, ie. on one side only. Further, while the connectors that are used seem solid enough, they are not the common mini-XLR used in the AKG K702, which means that you couldn't rotate after-market cables between the two AKGs.
Comfort and Isolation
What I found with the K812 is that it was very well fitting for me. The clamping force of the headband was just nice and there is never any fear that it may just slip off. And yet when i'm wearing the K812, I don't notice it is there even if I wear it most of the day. 
As you may expect from an open can, the isolation is moderate at best. 
Music Genres
I have a very wide repertoire of music in my music collection: all the way from medieval church music to Ella Fitzgerald, Billie Holiday, Frank Sinatra to Diana Krall, Holly Cole, Stacey Kent, Rumer to classic music to modern pop.
What is enjoyable about the K812 is that it is at least competent with all genres. There are some in which I find I do enjoy tremendously and that would be jazz vocals, opera and acoustic vocals. I have even listened to Calvin Harris and Above & Beyond on these cans without any issue. 
I don't actually worry about finding particular genres to listen to when I am on the K812: I just pick any album on the JRemote on my iPad and just hit play with full confidence that nothing but realistic and organic goodness will fill my ears. 
Sound Quality
The K812 are very well balanced: the trebles are extended, the mids are full and have a lovely timbre, the bass is deep yet tight. On top of this, the K812 has a wide and deep soundstage while maintaining beautiful layering, accurate imaging and excellent details.
Of course, there have been reports of tizzy trebles, but to date I cannot say I have heard any. As for some critics claiming that its soundstage is not as wide as the HD800, whilst that is true, the depth and layering of K812's soundstage cannot be beat. And it does make for a much more organic and natural representation of the music.
What I will say is that next to only the Abyss, this is the pair of cans that has the capacity to take my breath away or move me so.
I currently run my AKG K812 with Toxic Cables Black Widow. I wanted a fuller and more detailed sound from the K812 - no change in basic sig of the can but something which could communicate more than the very sad stock cable. On a side note, AKG K702 owners will be glad to know that AKG didn't discriminate against the K702: the stock cable of the K812 is just as flimsy.
My desktop rig at home comprises of a modded Mac Mini (with external linear PSU), Bricasti M1 DAC and then balanced out to the Bryston BHA-1 and RCA to the Woo Audio WA2. I will say that I am particularly fond of the sweet organic sound, with a wonderful intimate soundstage, that the K812 produces with the WA2. Of course, I also run it off the Bryston, with which the soundstage opens up and the K812 is more dynamic.
In my cosy little musical universe, the AKG K812 comes only second to the Abyss in the pleasure it constantly gives me. This is a pair of headphones which are organic while being transparent  and detailed. AKG rises again!
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I read somewhere about the break in period which is a concern if you have 30 day money back guarantee. Please let us know if they change in the next few weeks or so...
Hmm... I don't see it as a problem. The burn in period simply settles down the bass and trebles, and opens up the soundstage. Usually within a couple of weeks, the sound more or less settles. Hence, you will know before the returns period expires.
Thanks for the credit in the review. The K812 is without a doubt, a marvelous headphone worthy of its flagship status.
Pros: spacious, good separation, natural and even across the spectrum
Cons: expensive
i've read a number of reviews around the net which criticize the k812's for harsh treble and limited bass - all i can say is that my experience with these 'phones does NOT bear that out. the bass criticisms appears to come from people who want to listen to dubstep. i don't know what dubstep is. the treble criticisms come from people who are listening to some types of pop music with which, again, i am not familiar.

i am using these phones sourced out of an ibasso dx90   i am listening ONLY to classical and jazz flac files, and the sound is wonderful.

for example, i spent time last night comparing 4 versions of schubert's "death and the maiden" - and the source and phones revealed significant differences among the performances. they revealed not only the obvious ones of tempo, phrasing, and expressiveness, but also differences in how the groups were miked and/or sound mixed/engineered.

the lindsays sounded as if they were recorded while playing in a warehouse, with an open, hollow and slightly distant tone, especially for the cello which sounded a little muffled or veiled. the alban berg quartet and the takacs had a better sound, very clean and present, while the melos recording made me feel like i was sitting amongst the players, and could feel the bows being drawn across the strings. the high notes in the andante movement were intense, expressive and clear- very much revealed by both the source and the headphones, without any sibilance or "tizziness."  in the melos version, the cello was rich and more present throughout in a way that i very much enjoyed.

i then spent an hour or two listening to jazz. charlie haden and pat methany's version of "first song (for ruth)" showed off haden's bass work. the bass notes were deep and rich, the sound of the strings being plucked very clear, while also being tightly controlled without any loose or blubbery sound. the piano on jacky terrason's "nardis" was very much present, not at all recessed or veiled, across the full spectrum of the instrument. some brazilian jazz-pop by maria rita carried the vocals forward. they were lively and caught her occasional slightly gutteral or raspy sounds.
through all the music, classical or jazz, the phones presented a spacious soundstage, with good separation of instruments, but with the size of the soundstage varying with the recording.  in the schubert, for example, the lindsays had a 180-210o wide soundstage, while the melos quartet was spread over only 120-150o.

bottom line: i'm very happy with these headphones.  i can't speak to their application for other forms of music, but for what i want to listen to, they're great.
edit- to add a note about comfort- i listened for several hours yesterday and there was no fatigue. they're extremely light and comfortable, so much so that i didn't even think to comment on it.
no i don't, so i can't give you a comparison.  if the price is not TOO big a factor, let me recommend razordog's "open box" either through ebay or [for a bit more if you - like me- don't like using paypal] from razordog direct.  that's how i got mine, factory fresh.
Can you compare to any headphones?
I originally felt the HD800 to be balanced but after shopping around felt they were a bit light on the bass.
Though I think the biggest factor is the genres you listen to.
Classical / Jazz don't really need a strong, present, tight, thumping bass.
the only other high end headphone i have is the hd700.  i tried it on the dx90 and it was dull and lost all its soundstage, compared to driving it [hd700] from the heaphone out on my integrated amp [nad c375bee].  i realized later, however, that i only tried the on hd700 on the low gain setting of the dx90, and it probably would have benefitted from trying it on higher gain.   the k812 on ON THE DX90 compared to the hd700 ON THE INTEGRATED AMP [so different sources]: the hd700 had a deeper soundstage, although it wasn't all THAT deep.  the k812 ON THE DX90 has a big, but more of a two-dimensional stage- with great separation and  good "air" or space around each instrument.  both have really good, rich tone - but i didn't go back and forth to compare them.   the k812, with only 36ohms of impedance and good sensitivity are easy to drive with the dx90.  sorry i can't say more than that.  i agree that what music you listen to might make an enormous difference on how happy you are with any headphones, and that's why i was very specific about what i was playing.  
the k812 seems to be very even across the sound spectrum, with good representation of very high tones [on violin or piano, for instance] right down through the mids to very low tones [e.g. cello, bass, piano].   this evenness is great for what i want to listen to, but e.g. probably wouldn't satisfy a basshead.
Pros: Big soundstage, good for monitoring
Cons: But not good for music listening. Very hard to drive.
This is the first time I give a lower than 5 star rate. The reason I say tha K812 is not good for music listening is because K812 seems to has it own way to illustrate music: it seems like K812 likes to confine every piece of music in a certain room with a stress of bass. This is good because that will ensure you hear something familiar every time you use K812. The strong signature is definitely for pros who do not want to waste time getting familiar with a headphone again and again.  But for those who are not basshead or those who want to hear "music free in style", this strong signature is a big big big problem. 
The sound is a bit dark, detailed but no way balanced. To much bass; imaging is good in a bad way (Clear, wonderful imaging, you can see everything but the singer seems to be in an awkward position: behind/is the drumer) treble sounds uncontrolled like hell if you don't drive it properly; sounds depressing as if I was listening via closeback phones
Bottom line:  Remember these are monitor headphones. Don't waste you time if you are not a pro. 
Champ HkGt
Champ HkGt
It's easy to drive, I Think.
This review is completely wrong ! 
Hard to drive? I cannot relate. They can be driven even by a smartphone (certainly my iPhone 6 can do). If you have a nuforce uDAC 5 - even that can drive them. The Chord Mojo drives them effortlessly, adding just the lightest of smoothness to make the experience great. 
Beyerdynamic T1, Sennheiser HD800(s) - those are hard to drive.
The sound is not euphonic, but it is so revealing that I can locate there the air conditioning is in some recording venues.

They can be cruel, but they are not harsh (sounding).
Pros: natural sound, high resolution, great imaging
Cons: unforgiving, sometimes tizzy
Review AKG K812
Regarding the craftship and comfort I can just say: It is really top notch and compares to the world bests favorably. The aluminum parts look very nice and the design is a future classic. They look much better in real than on any photo. The only down side is the cable. While the Lemo connector on the headphone is excellent quality the rest seems to come from a 50€ can. Aftermarket cable maker will make a fortune. There is no chance to use a balanced cable without extensive mods. In short the cable is a shame for the asked price.
The headphone was burnt in with >100h and all comparisons were made after level matching with pink noise.
The focus of this Review will be a comparison to the standard recommendations in the >1000€ (or $) class. The main contenders will be Sennheiser HD800, Hifiman HE-6 (on a great speaker amp like my PASS Aleph J) Audeze LCD2 and my personal reference for a monitoring headphone the STAX SR-X MK3 PRO.
Regarding the reference phones not mentioned in the review I can just state that the Beyerdynamic T1 is clearly beaten. The Audeze LCD3 and TH900 are technically good they are colored while the K812 is a monitor with a flat frequency response and has better detail retrieval. It is even more neutral than any now in production Stax phone except SR-009. The sound has an airiness and resolution that reminds me a lot of my beloved electrostatics.
Even AKG claims, and many users restated it, that the K812 is easy to drive I don't agree. Of course the high sensitivity doesn't call for a lot power. Out of the iPhone, iPod, iPad, Centrance Hifi M8 I had the impression of a too bright can. Nevertheless out of the iPad its sound quality beats all over ears I have heard to date directly from an Apple device. But the K812 sounded much better out of the Bryston BHA-1 and Violectric V200. The soundstage just opened up and the slight sibilance became less.
The K812 is in this area simply world class. It is on par with good electrostatics and a well  driven HE-6. I can not get what Tyll heared here when he stated the the HD800 is is a higher resolving headphone than the K812. In my opinion the K812 wins quite clear.
Well balanced sound over the whole frequency range. It reminds me a lot of my Stax SR-X MK3 PRO and that is the most honest and sometimes even brutal revealing monitor I have ever heared. So AKG has really met the goal of a professional studio monitor. Only the highs are sometimes a bit harsh specially with not optimal recordings.
All instruments on the K812 sound very real and life like.
 More bass quantity and quality than the HD800. The picked bass notes of a contrabass are easily discerned. Nevertheless it is beaten by the bass of the HE-6 and LCD2. They go substantially deeper. Even with the Bryston BHA-1 the K812 the sub 30Hz bass is nearly non existent. And the deep tones of the orthodynamics are firmer and more on the dry side. Maybe this is the result of the measured high distortion in the K812 bass department.
The cleanest mids I have ever heared in a dynamic headphone. The mids are slightly less neutral than on the HE-6 and Stax SR-X MK3. But compared to the K812 the voices on the Hd800, LCD2 or Denon AH-D5000 are kind of too fat. They add a warmth that is not in the recording.
This is the first point for me to criticise.  The super heights >10 KHz are excellent. But the 8. Octave is not done well. It has a 6KHz peak like the HD800 but it is less prominent. And then there is a second peak in the lower treble (3-4 KHz). This might add to the impression of the extreme high resolution in the voice department. The K812 is also slightly sibilant, even more than other bright headphones light HD-800, HE-6 and AH-D5000.
I can get why Tylls' first impression was tizzy. With a little parametric equalization the Problem is easily solved. (-3 dB at 3.5 kHz and 0,3 oct. Bandwidth + -2dB at 6KHz 0,3 oct. Bandwidth) I used Beyonces ingenious 'Single Ladies' for those tests.
The K812 rules this category, it is simply on par with the best I have ever heared. Each instrument and voice has a well defined place and there is plenty of air around it. The only headphone I know of that is better in this is the pricey Stax SR-009.
 The depth is as good as the HD800 but it is much wider with the Sennheiser. Especially with symphonic music is the difference quite big. The Soundstage is  comparable with the HE-6.
The AKG shows clearly any change in the chain feeding it. I have never found a headphone that acts so sensitive to the change of the DAC and amp. Especially bright sources or amps like the Mytec DSD192 or the CEntrance Hifi M8 make the K812 even more sibilant.
The K812 lacks completely this attribute. It is a studio monitor and can sound brutally honest. Friends of the TH900 or LCD2/3 will always miss something with the AKG. Even the HD800 ads a more mellow sound to voices and the very neutral HE-6 sounds more euphonic. 
Recording Quality: The K812 shows merciless any mastering error.
A slight noise floor in the background will be revealed more than with any other phone except my Stax SR-X MK3 pro and that is the most revealing can I ever found until this day. Bad recordings are a torture with the K812.
Now a few comparisons with music samples
Beethoven Symphony 9, Leonard Bernstein, Ode an die Freiheit Like mentioned before I think the HD800 is better for big orchestral music. With the Sennheiser you have the feeling of watching the stage of the Berlin performance from the 4th row while you sit on the stage with the K812. But the tonality of the K812 and HE-6 is better here. The huge resolution of the K812 is really amazing. You can hear many details of the ten thousands in the audience like somebody sneezing another dropping something etc.
Miles Davis, Kind of Blue
I like the soundstage and imaging of the K812 better with this classical album. The smaller and more intimate presentation is more like the original setting (I know this recording nearly by heart with many stereo systems). To hear the slapping of the Bass, Evans piano strumming and Davis pressing of the valves is simply stunning. It is as detailed as the Stax SR-X MK3 pro. Only the sub bass of the LCD2 is quite a bit better and the piano sounds more natural with the HE-6.
Kodo, Heartbeat Drummers of Japan
The LCD2 is a force with this recording. You can nearly physically feel the size of the big drums and that is a quality you don't find on the K812. But all the details of the noises around and the sticks hitting the drum are really impressive. And the imaging is more precise than the HD800. With this album I see a draw between the K812 and my HE-6.                            
Kings of Leon, Mechanical Bull
This was the surprise of the listening session. The AKG was amazing good with this record when compared to the alleged rocker LCD2. The Audeze sounded slow compared to the K812. But the HE-6 made the guitars sounding more real.
Leonard Cohen, The Essential
Cohens voice is my personal standard for how real and lifelike a headphone sounds. Every can presents that rough voice in a different manner. The K812 presented his voice quite nice only the female background vocalists sounded sibilant sometimes. The HD800 makes the voices sounding more beautiful than they are by adding some weight to the 4-5 octave. The K812 is more true to the recording here. Nevertheless the HE-6 stays my favorite.
The K812 is in the sum of its attribute the best dynamic headphone you can buy new at the moment. It is a genre master as long as the recording is good.  He wins on the Bryston BHA-1 even against my beloved HE-6. But on a Pass amp the Hifiman flagship is still another beast and wins by a small margin. And my SR-X MK3 keeps the crown of the most accurate headphone.
I would not recommend the K812 as sole headphone. For bad recordings you would need something more forgiving like an Audeze, Denon D5000/7000, Fostex TH900/600, HE500 or a HD650.
But it is an excellent choice for those looking for a real high resolving can.
Thanks cucera, that's gives me a good reflection of where your'e coming from. I've never heard the Stax but I agree about the LCD 3 and the HD800.  I'd be using the K812s with  portable rigs: AK100/Chord Hugo  and ipod classic/CLAS db/CL Duet. I think the Hugo would drive them well - it does a wonderful job with the HD800s and especially the LCD3s. It's interesting to read paulchiu's comment above because the TH900 was another option I was considering for the more intimate,  singer/songwriter and small acoustic repertoire. I don't know why, but I have the impression the TH900s would be more recessed and warmer than the K812s for this kind of music? Thanks again for your help.
Great review!
To people who is reading takato 14 comment on thin diaphragm, the logic it is off. Have to view magnet and diaphragm as a system that interact with one another. Change in one causes change in the other.
Q: Diaphragm breaking up (every break up = distortion) is due to what?
A: Due to too much force applied to the diaphragm.
Q: Where does the force come from?
A: Strong permanent magnet, pushing and pulling on voice coil (electromagnet) attached to the diaphragm
Thus if we reduce strength of the magnet, reduce force applied to diaphragm, which no longer breaks up. OR use a stronger diaphragm. It is a system can't view it one sided... PS **Not actually saying K812 has diaphragm break up but if it did that is the process.
May I know how to set this up in fabfilter Pro Q2?  What is the Q factor?
-3 dB at 3.5 kHz and 0,3 oct. Bandwidth + -2dB at 6KHz 0,3 oct. Bandwidth
Pros: open, detailled, neutral, analytic
Now I correct the Google translate - I use http://www.dict.cc/ and my (small) knowledge of English 
I hope its a bit better now! :k701smile:
AKG K812 Pro
Type: open.back  dynamic headphones
Sensitivity: 110 dB SPL / V
Rated impedance: 36 Ohms
Max output power: 300 mW
Cable: 99.99 % oxygen - free with genuine LEMO connector
V- WCBV @ 94 dB SPL = 300 mV
Magnet: 1.5T
Net Weight: 390 g
More about: http://www.akg.com/k812-1308.html
My first impressions that can not yet be final. And, I accentuate always, these are my personal impressions without any claim to absoluteness!
High-quality packaging, covered with black cloth, hinged lid, fully molded tray, headphone stand made of laminated wood.
The essential parts of the K812 Pro headphone are made of high quality aluminum. By a gimbal mounting, the seat fits perfectly on the head shape.
The bracket can be adjusted by means of screening. The seat is good.
The K812 Pro is designed as an open headphone. The openness is not visible on photos, because the perforated back cover is additionally covered by a fine mesh, the driver is also protected by a fine mesh. In a way, in my opinion he is closer (in terms of openness) to the legend K1000 than the K/Q7xx series without its disadvantages. Of course, with newly developed 53 mm drivers of all previous innovations (eg, magnet 1.5 Tesla, lighter coil wire, etc. ) are included with.
The pads have approximately the same inner diameter as the K/Q7xx series but are constructed differently, include the ear perfectly and closed with a kind of lip to the head. The cover of the pads is velvety, leathery (a reference to which material they use, I dont found), comfortable to wear .
Tonal the K812 Pro are best headphones I had in the house to test so far. It is in any case to be classified (ranged) over the Denon D7000 (also ranged over the Beyer T1 as I could compare this with in the pre-test ). This refers to my test of pilot run model ( AKG ) and the first hearing impressions and does not constitute a finally statement.
As I recall, he is tonal ranged over the K1000 legend. Alone, the bass of the K812 Pro ranges noticeably down much deeper . The comparison with the K1000 regard to the openness of the stage I can not reproduce, since I have no K1000 available and memories I want to leave me any way.
The K812 Pro is neutral as it should be for a studio headphones, but also relentlessly against bad recordings, errors in the recording - which indeed corresponds to the actual purpose .
The audible sensitivity - my headphone amplifier WNA MKII with 15 Ohm output impedance is the difference in volume level for K712 Pro rather low, I just have very little to regulate (direction down) to the same volume to achieve.
First impressions sound to see with caution since no burning in period.
Sara K. " Hell over high water" SACD -DDD
Tend to track a noticeably brighter and richer in detail and better, finer resolution than the K712 Pro.
Neutral, profound, punchier but not over emphasized bass.
Liszt Orchestral Works , 2CDs , ADD
Berliner Philharmoniker , Herbert von Karajan , recorded in 1961 , 1968, 1976
Very high and fine, detailed resolution of sounds. Expansive deep bass, dry, without the boom in the mid- bass range (as sometimes occurs when Denon D7000) .
Comparisons and impressions regarding the spatial representations stage will coming soon, please be patient, I will check here some of my impressions after a few days again. Now I'm a few days so just listen and take notes. If I heard, "a block of my test pieces", I report. So far as I always did with my hearing test!
Photos will follow soon, I need to edit (examine, reduce resolution).
PS: Regarding the Availability, as far as I know,  next week the first copies go to the dealers and processed the pre-orders in order. The production in Vienna operate at full stretch. Please bear with!
and pics
Impressions Part 2

I am referring mostly to details of recordings that I know very well and have often heard with different headphones. I describe here my feelings here.
Pink Floyd, The Wall, 1979
A few highlights :
CD1 Track 1 , 1:40 to 1:50
Echo of the singer - right, left - precise, clear plastic
CD1 Track 3, finally
Helicopter - "I pulled down my head, in spite of headphones"
CD1 Track 4 - only Live can sound even better
CD1 Track 5 - finally, the cries of children, audible right outside the head in space
CD 1 Track 8, Mother, one of my favorites - with perfect "heebie-jeebies shiver"
CD 1 Track 7 , guitar strings sound metallic correct and not wrapped in cotton wool around - as if they were playing live in front of me.
CD 2 Track 6 , the door knocking sounds very realistic, live character.
At Pink Floyd music abundant background noise are perceptible, precise, plastic, spacious (some with 3D effect) reproduced. Between individual voices and instruments is enough space, they are reproduced clearly and distinguished from each other. The overall picture remains homogeneous.
Marianne Faithful , Blazing Away, AAD , 1990
track 1
Applause, clapping of individual hands are very good audible, it does not go below a noise floor .
Track 3 , 0:20 to 0:30
delicately battered drums brass, metallic and very authentic.
Track 8 , 2:50 to 2:56
The lightweight dab the drums brass with the stick very well resolved, metallic, authentically.
Drums - very detailed, individual cymbal well of each other audibly separated, highly differentiated as did the musicians.
Magic of Himalayas , Mystical Scent , xxrcd ( JVC , Japan Import )
The Ultimate bass test , this CD brings the most impressive bass my collection in itself , makes even the legendary Telarc recording " 1812 " and the Japanese drummers (such as Kodo ) in the shade.
track 1
The very deep rumble of the drums is very impressive place (for a fully open headphones).
Track 1 with greater volume, not overdriving the bass noticeable.
The rest of the CD, punchy , accurate bass, instruments delimited, with enough air between them, the sound still remains homogeneous. On this CD "walking" some individual instruments between right and left, back and forth, which is mapped from Pro K812 very well spatially .
The "black" deep rumble on some of the recordings will be played very punchy.
The stage is wide, spacious, the voices of the singers and instruments are staggered in space.
more about coming soon