AKG K 550


100+ Head-Fier
Pros: Transparency, soundstage, treble
Cons: Comfort, perfect seal
This is my first review so please be gentle!
When you first put on this closed headphone, you'll be stunned how wide the soundstage is. Compared to my open Sennheiser HD600, the soundstage is equivalent! (though the HD600's soundstage is slightly deeper).
The K550 also trumps the HD600 in so many aspects including transparency, clarity and dynamics. On the other hand, the HD600 trumps in bass slam and comfort.
There is plenty of bass in the K550, but it's not as textured as the HD600 and as for comfort, the cups are really comfortable but the headband requires more padding.
The amp I used to to compare the HD600 and K550 was an Aune T1 with 6922 tube. I've only just upgraded the tube to a 6H23N-EB and the K550 sounds even better, but unfortunately I don't have the HD600 handy right now to compare on this new tube.
The value of this headphone is unmatched given how good it sounds and is possibly the best sounding closed headphone that is still in production. It's currently my favourite headphone for music, and in case you were wondering, this is my headphone preference:
AD700 < M50 < FA-003 < DT770Pro LE < HD650 < HD600 < K550 baby!
I think that your order of ">" is incorrect. (opposite).

I would be surprised if you find the M50, AD700 surpass the HD600s!
Thanks Chimp, now corrected :)


New Head-Fier
Pros: sound quality, design, materials,
Cons: permanent cable
Maybe the best closed headphones for this price. 
Very well designed. I´m very pleased about the design, it´s simple, elegant, clean but still extremely cool. There´s not much plastic on the headphones, almost everything is either magnesium or steel. They feel pretty though so they hopefully dont brake that easy. Earcuffs are soft, very soft leather and it feels really good on ears. Overall the design is very good!
Then the sound...
Well what can I say... I really love the sound of these headphones, its well balanced, nicely bright and still so smooth. I just love them.


New Head-Fier
Pros: Great for R'n'B and Hip Hop.
Cons: Top end can be a tad harsh, fit isn't perfect.
My last set of cans have all been Sennheiser's, (except a pair of Shure SRH550's which were very thin and uncomfortable).   Sennheiser Momentum's were top of my list next to the HD598's.
My music tastes are very vast, but commercial, varying from Boyz II Men, Bruno Mars, to Bon Jovi, Kings of Leon, to Biggie and Jay Z.
My normal listening kit are Monitor Audio speakers, Quad L sub and Yamaha amplification, which has a very good sound-stage, outstanding clarity with very deep musical undistorted bass.  This is what I was looking for in headphones.
I demoed the Sennheiser Momentum's against my old Shure's and Dre Pro Beats.  To be honest I wanted a combination of all three.  The build of the Beats, the clarity of the Shure's and the beefier bottom end and thicker mids of the Momentum's.  I did walk away a little underwhelmed as none of the three had the sound I was quite after.
After researching this forum the K 550 turned up on the radar and considering the HD598's are open and I was more after a closed phone, I jumped on the K550's, but nervous that I was going to have fit problems and the bottom end being thin like the Shure's.
K550's turned up and I plugged them straight into my phone as I was on my way to work.. underwhelmed and a bad fit..... till I got home after spending the afternoon carefully bending the strap to get a tighter fit, works and they actually fit now like a glove.
Plugged them into my Yamaha amp turned them up pretty darn loud and left them over night... next morning had a good listen.
Setup: 320kbps music via 360> HDMI to Yamaha amp set on "Pure Direct", which turns everything thing off that's not needed and is the cleanest feed it can deliver, which is noticeable.
Bass is something I can't believe people say they don't perform with!!  They aren't as dirty or forward as the Momentum's, but have punchy, clean, deep bass that doesn't disturb vocals one bit.  Hip-Hop or R'N'B are my fave styles of music, which these really perform outstandingly with.  Vocals are amazing with rappers such as Jay-Z, Nas, Tupac and Biggie, smooth, excellent clarity and very easy to listen to and capturing every lyric effortlessly, which the Momentum's slightly struggled with and the Beats surprisingly stink with certain tunes (Biggie's 'Juicy' sounds amazing through the Beats, but then 'Dead Wrong' is just a mess!).  More musical tunes, like Eminem's 'Space Bound' really do sing with a nice sound-stage, but with the added treble the phones are a tad too bright to have them quite as loud as other hip-hop tunes.
This follows R'n'B and soul artists too..  John Legend, Seal, Michael Bolton and Lionel Ritchie all sound absolutely fantastic with these, great sound-stage and their velvet voices really, completely complement the sound of the headphones, but certain tracks from such like when Boyz II Men go Acapella with 'It's So Hard To Say Goodbye To Yesterday' the high mids do resonate at loudish levels, which does force you to turn the track down a notch or two, but when 'The End of the Road' comes on the next track.... absolute bliss.. an absolute joy.  Really enjoyed listening to Bruno Mars and Alicia Keys absolute cracking fun with tracks like 'Runaway Baby' very fun, both artists have bass friendly tracks mixed with lots of different type of instruments still easily heard, even the discrete ones!!
Overall I'm very happy, they're not perfect and I wouldn't say they're worth their RRP, but at thier current price they are fantastic!
"Bass is something I can't believe people say they don't perform with!!" yeh you will find that around here alot, some will say the headphone is boring and have no bass and wont recommend it, but when you try it you have to wonder what ere they listening to, but you will find they recommend headphones with strong bass and recessed mids and give them praise...it puzzles me too
Michael Bolton? Boyz 2 Men? Dang, you are a brave soul.


New Head-Fier
Pros: nice isolation, comfort, design
Cons: i miss open HP signature in sound, Highs is quite in backround
Litte bit bassy headphones, bass go deep enought. Highs can be better. Mids not bad.
But i havent fully burned pair of these nice HP.
I am Gradist :)


100+ Head-Fier
Having owned quite a few closed back headphones I have never experience the open sound these AKGs produce. Yes they may be light on bass but they excel in every other quadrant. Detail, tone and space ooze from these headphones and draw you in. At this price point I would dare to say they are unmatched if you want a truly uncoloured musical listening experience. One snag is people with smaller heads may not get a good seal around the ear cups which will ruin the experience. Try before you buy!
  • Like
Reactions: taffy2207


New Head-Fier
Pros: Clear, Articulate, Powerful, Wide sound stage, Easily driven, So Comfortable, Extremely solid build quality and $300!
Cons: Long cable (braided it, perfectly fine)
I have loved these headphones since I picked them up out of the box. They are mostly metal with thick, soft, leather pads and sit on your head very snugly (and if they don't for some reason you can bend it slightly, feel free to message me if you have questions). They produce excellent sound and with a solid burn in it only gets better. The soundstage will open up and the overall sound quality improves greatly. However, one annoyance for me was the long cable which I just braided, afterwards no problem at all. Also I bought an extra pad for the headband for when I want a super snug fit and I highly recommend getting one (http://www.amazon.com/gp/product/B00862522A/ref=oh_details_o06_s00_i01 its a stretch but it will fit, keep trying). 
These have an amazing sound and they are awesome all around headphones for whatever you genre you want to listen to. You wont be disappointed 
  • Like
Reactions: Simurgh
Nice review with good tips so thanks. Still, I'm not quite sure what you meant my braiding the cable so I can only imagine that you place some sort of sleeve over it and that somehow provided some kind of benefit.

Tim Maestas

New Head-Fier
Pros: Amazing for vocals and high quality live recordings. Batman approves of the styling.
Cons: Bass light. Comfort.
I love mine! They're great with most genres. I wouldn't complain if there were a tad more bass, but it's really not all that lacking. While the earpads are super comfy, the same can't be said about the headband. It's a bit flat on the top, and not incredibly padded, so unless you've got a similarly flat dome, long hours can cause some tenderness up top. Again, not terrible, but just a note. One thing about wearing them out, and I you will be worrying far too much about banging them on something (only downside of them being so darn good looking).
I love my K550s but agree with you on the slight discomfort with long term use. Try this http://www.amazon.com/gp/product/B00862522A/ref=oh_details_o06_s00_i01
when you get it don't worry about the fit, just keep trying and it will snap on. once it stretches out a little (I left it for 24 hours) it will just stay that size. Its also pretty good reversed so the darker cushion is on the inside with the smooth part against your head.


New Head-Fier
Pros: Sound is spotless. Design is nice and clean. Like Crocs are to your feet, the AKG K550 is to your head, nice and comfi.
Cons: No detachable cable.
When i first saw the AKG K550 i was blown away. The design was so unique and very good looking and when i listen to them i was blown away just more. I bought them without hesitation and hurried home with my new badboys. I have now had them for 3 months, and i have been happy for them every day since. I wish that hearing them was a part of  this review, because the sound is phenomenal.
Sound quality:
The bass is very deep, soft and round without getting muddy.
The mids is extremely rich and powerfull.
The highs is 100% clear.
Overall this headphone sounds terrific. Some even say that they sound like an open hedphone, but i would not say so that they do. I understand why people say it, because the highs and the mids can have a trend to sound like a open headphone, but the bass is to deep and different then a bass on a open headphone. Let me put it this way, i would much rather listen to Rap music on a pair of K550's then i would do it on a pair K701's. And with that said, it dont mean that the K550 is a headphone with a overpowered bass, the bass is still unobtrusive, but you will notice the bass. I have listened to a lot of different artists, from Tom Waits to Lou Reed, from Katie Melua to John Mayer and the headphone is perfectly balanced from the bass to the highs!
Sound leak/isolation:
When you take them on, and turn the volume up to about half you can't hear anything around you! But what about people around you, can they hear what you hear? People with big heads will not have any problems with them leaking sound! But people with small heads will/might have a problem with sound leak. Because the earcups are so big, and you have a small head it might give you some problems. But otherwise, you will NOT have any problems what so ever!!!
Build quality and comfort:
The are all metal so they are pretty steady, and suprisingly they weigh nothing. It was somthing that really suprised me at first, they only weigh somthing about 300 grams. And with that weight the are really comfortable to use in longer periods of time! If there is one little thing to point fingers at, it must be that the earcups ain't in lether, but in plether. they are still very soft and nice, but i would just have loved to see some real lether on it......
simply outstanding, no need to say more!!!!!!!!!!!
Check out my homepage for pictures...
  • Like
Reactions: Simurgh
Thanks Anhoblack for the time and work to a very well structured excellent review which covers all the angles with plenty of oozing satisfaction :D
Well I agree on most parts except for the fact you called it balanced. To me it sounds like a v-shape signature. A little bit thin.
Bass light (ignore the FR graph) has resonances in the upper mids, and treble is monstrously boosted.
I speak the truth, as for the resonances - when you notice, it will ruin them for you.


Pros: detailed, clean, balanced, no need of powerful amp
Cons: unexciting, harsh on some frequencies
It doesn't really need amp, but it benefits from them. My ears got tired of listening to them.


Pros: Great build quality, Comfortable, detailed, well-balanced open pair-like sound
Cons: Too big for small heads, non-detachable cable
I'm not an advanced audiophile. I'm a senior high school student who loves headphones and decided to invest all his money into a proper set of cans. 
Coming from a pair of bass-modded HD448's, as well as the PortaPro and a couple pairs on in-ears running though my Fiio E7, my review is purely subjective, therefore I'll keep it short.
From the very first moment I put on the K550 and started listening, I know this is a completely different league. The amount of detail is blistering, I immediately felt like I've always been listening to only half of the music. Doesn't matter which genre, there is just so much more to hear. The bass goes far more deeper than I've ever known, the mids give out such amounts of depth and detail, you start to hear each guitarists finger slide over the strings, every punch/tone played fading away. While your Portapro's sound travels into your ears, the K550's sound will surround your head, which such detail, you will never want to go back once you get used to them.
I can only judge according to my own experiences, but for the owners of sub-100$ cans: If you chose to take the next step, this pair will blow your mind.
Thanks for the review. Interested in getting the AKGs and currently have the HD448. How would you compare the sound between these two?


Pros: Amazing build quality, open sound, closed headphone
Cons: so big! And cord isn't detachable.
These headphones are fantastic!  
Build Quality- These are the best built headphones I have ever seen.  They are all leather, pleather, and metal, and feel tough yet very lightweight.
Comfort- These headphones are unbelievably light and comfortable, but they are so big that some people have complained that they feel like these headphones swallow their heads.  If you have a small head you might want to reconsider.  Also the leather earpads have foam inside, which is comfortable, but not exactly the sort of feel I was expecting.
Sound-  as a previous reviewer said, these have two bumps in the bass.  However, the bass is understated. I personally prefer a bit more bass, like what you get with the Pioneer HDJ-2000, but overall these are so much better than the HDJ-2000 that the bass is an easy sacrifice.  Also, they are very open and neutral sounding, so if you like Grados or Beyers (that light rock-and-roll type sound) then you will very much like these.  To me, they sound better than even some of the high-end audiophile closed Sennheisers and Audio Technicas that I've tried!  They especially excel in jazz, classic rock, and strong vocalists, like Tracy Chapman.  Snare drums have lots of sizzle and pop, and the huge 50 mm drivers really capture all the lightest conotations of the high hats and ride polyrythms.  I'm a drummer, so I pay a lot of attention to the drums, but this level of detail is present in everything else, too.
Aesthetic-  There are a lot of memes on the internet about "swag is for boys, class is for men."  Anyways, by that logic, if beats by dre pros are for boys, then these are for men.  They have that same confident, sexy look, but quite a lot more refined and sophistocated.  As one reviewer put it, "They look like Chubacka or James Bond might wear them" (I'm sure I did not quote that verbatim, but you get them point).  They look stupid around the neck, though, because they're so big.
Complaints- These are so big!  I guess it's worth having big cans in order to get that big sound, but still!
Also, for $315, you'd think they could throw in a carrying case!  These things are expensive and I feel bad just chucking them in my backpack.  I'm really pushing that Best Buy warranty to the limit!
Lastly, why not have a removable cord?  It seems impossible that a pair of headphones so big wouldn't have room to make the cable removable.
Bottom line- these are arguably the best closed headphones in the $250-$350 price range for non-=travel and non-portable applications.  I highly reccomend them.  If you want something more portable and with more bass, check out the Philips Fidelio L1 or the Pioneer HDJ-2000 (better in black, get the K!).  However, these do sound better than the L1 or the 2000, so if sound comes first, these are the headphones for you.  Kudos and good job getting over the whole lame-copies-of-that-headphone-nobody-likes phase you were in, AKG, and I for one hope you and Harmen continue the good work!
  • Like
Reactions: Simurgh
Most of AKG's headphones have 10 foot cables...
Nice review. I'll definitely be getting these after my K271 die!
Hi, I just wanted to do a quick comparison of the K550 with the HDJ-2000 for anyone interested.
HDJ-2000 is very good but can be a bit tight on bigger heads like mine, though certainly not what you would call a clamping headphone. In comparison, K550 is a bit too loose, so it moves around and does not stay secure if you are not staying still. Both get 4 out of 5 stars.
The K550 sounds better in the way that Da Vinci is a better artist than that guy who invented James Bond; sure, the K550 is amazing, but on a sunday afternoon most people would rather see the new bond flick than look at some old dead guy's paintings. If the K550 was a little less balanced I would like it more, but they were going for that "open" sound and they certainly got it! 5/5 for K550 and 4/5 for HDJ-2000.
For two of the best-built high-quality headphones around this is a tough one, but because of the lack of folding capabilities the K550 is a bit tougher. 4.5/5 for HDJ-2000. 5/5 for K550.
After dinner listening to jazz you want K550. At school jamming to some rock and roll or hip hop you want HDJ-2000. I've never tried the Fidelio-L1 but hear it's somewhere in between. None of those three noise cancel; in fact they barely even passively isolate.
pm me or comment with any questions.


100+ Head-Fier
Pros: Comfort, isolate very well
Cons: Very long cable
Bought as upgrades to me 13 year old Sony MDR-V600s.  Can't really assess their audio quality, other than to say they're a clear upgrade from the MDR-V600s.
I bought them for computer use, both gaming and .flacs.  Performs very well at both.  Can be worn for hours on end.  Cuts out ambient noise, and so far my wife hasn't complained about being able to hear them when she's working in the same room.
Tried using them on the bus, but they're not terribly well suited for portable applications. The cable is long and straight, and overall the set is a bit big to be carted around.
Still, very happy with the purchase.
If you can't assess their audio quality you shouldn't rate it 5 stars...
Maybe a 4 will be fine, because it has serious issues. That resonance in the upper mids is a deal breaker for people who have hear its competitors.
Although for an isolating, comfortable, well built, closed can with monster soundstage its definitely got its pros. But its best suited to games and movies. Not music.
Not sure what you want me to say or do. I did not rate them 5 stars in anything. I also clarified not only my experienc, but how I use the headphones - with computer gaming being a healthy part of the mix.
I've seen the graph, and I've read your review and rhythmdevils. It's nothing I've heard myself. If and when I do, you can bet I'll change my rating. In the meantime, the review will continue to reflect my current experience with the headphones. If anyone has any advice on how to better clarify in what way that experience is limited, I'm open to suggestions.


We intend to hurt him...quite a bit. very_evil_smiley.gif
Pros: Soundstage, Imaging, Isolation, clarity (for the most part) and construction
Cons: Resonating upper mids that destroys musical pleasure.
RythmDevils review covers everything so I am going to keep this short.
It has issues, I have burn't it in plenty and used equalizers, and played with many variables. 
This is a strength of this headphone, it has amazing isolation and soundstage and imaging, even better then the Denon D2000 at this price, so for a closed headphone its a real treat. 
Personally I think it has too much treble period, but turning it down helps, the strengths listed above hold true, but Harmon Kordon clearly did not finish this headphone, and unfortunately it seems to be a trend for them to push out headphones with issues (AKG K701 for one.) The upper mids has a resonance to it that can drown out some portions of songs so badly its almost unforgivable. A good example is Lana Del Rey.
SO I would recommend this for movies, but not music, many people who have bought this still enjoy it, but most of them have noted something wrong, and the resonating upper mids is what it is. For people with experience with equivalent gear its a big issue, but as a first step into this tier of product the odds are you won't notice, but you shouldn't waste your money getting less then what you are supposed to at this price. 
AKG I am disappointed.... And I loved my AKG K242HD so much too.
Brownie points for you! Unfinished is right. Unfortunately most headphones these days are unfinished. They seem to have spent more time and money on the aesthetics of these than the SQ.
No seriously, i am calling them "unfinished AKG" from now on, gets the point across to newbies. I will say it does look damn sexy, and the build is a mile better then the AKG K242HD.
It was this and the fit issues affecting bass that spooked me away and towards an even bigger gamble...the Soundmagic HP100, their first full size, but eh. it gets great reviews and someone has to try em out.

tracylynn MkII

Pros: Good isolation, very comfortable, devilishly handsome, excellent soundstage and sound quality for a closed headphone at the price.
Cons: No detachable cord, not a closed K701 if that's what you want.
When I first came back home to this package, I couldn't wait to see what AKG had done this time for one of their fans. Quickly plugged it into the e7+e9 alongside the K702's and started up the music.
My first thoughts were that the detail and clarity of the 702's wasn't there, but then I realised that it was because I was having to actually focus on a more prominent bass as well as the trebles and mids! I had gotten strangely addicted to the dry analytical and distant feel of the 702's and my only other closed phones from this century I had were the Superlux 662B's (with velour pads) which had been collecting dust for some time. As I continued to listen, I realised that the mids on the K550's were really creamy and brought a smile to my face in a way the 702's couldn't. That isn't to say the mids on the K702's are bad, they are excellent, but for the first time I am seeing why some people may prefer to go for warmer sounding phones, whilst sacrificing some of the "true" sound of the music.
When listening to Bach's suites for violoncello the sound actually brought a lump to my throat it was so beautiful, with comparable clarity to the K702's but a closer and "friendlier" feeling to the instruments. I had heard people mention that these headphones were not compatible with classical music but I would definitely have to disagree. The soundstage is more than competent, and significantly better than my closed 662B's and I don't feel I would anger too many people if I said one could compare the 550's soundstage to that of an open headphone, and for this I really must applaud the people who worked on this beautiful product. The imaging may not be perfect, but I felt that I had more height than with the 702's, which feel like a flat plain which expands out into the distance, where the 550's are closer but more layered, which was noticeable especially when listening to choral pieces.
Moving on to techno music and the bass seemed overwhelming compared to the 702's that I had grown so used to, which again, worried me slightly at first, but I am starting to appreciate the bass more than I could really with the 702's. If I can I would like to come back to this again maybe in a few weeks or months time, to see how I feel about this. I would like to say that the kick the bass has to it is amazing and something I have not heard with my 702's at all, which makes me feel like I have been missing out, at least with some genres of my music.
Moving onto Toho@Arena, a song that starts with cymbals opening I really appreciated the crisp sharpnesss of these phones, that I find again are comparable to the 702's, but in the overall package of bass, treble and mids and how they work together in these phones, one gets in my mind a very different feel to the music than with the 702's and if anyone thinks they can get either headphone to substitute the other, I would have to disagree with them wholeheartedly.
I did however take this opportunity to test how much sound leaks *out* of the headphone by placing them flat on my wooden desk. At first I wasn't impressed until I realised the 702's were the ones producing all the music behind me. I unplugged them and was immediately taken aback by how little these leaked. I had them up to 10 o'clock on the e9, which is probably slightly above what I would usually listen to whilst on commute, and think that the person next to you on the bus would definitely have to be quite picky to become annoyed at the small amount of volume coming out of these headphones at normal listening levels!
As for fit, I have always found that despite the fact a lot of people seem to find AKG's difficult to seal on their heads, they always suit me just fine. As these headphones have a nice numbered system of notches on the metal, I can always know to go for 6 on each side, in case someone else has been wearing them. The numbers go from 1-12 and so in my mind they should be able to fit most heads without a problem, unless you are trying to fit these on a small child or have an exceptionally large head (no offence to anyone who can't fit in these!).
As far as comfort goes, the pads are made of pleather yet feel like a premium good and I am very happy with their performance. The padding on the headband is very small and takes a step away from the iconic self fitting AKG headband, to make these viable as portable phones without being laughed off the bus or train and are significantly more comfortable than what feels like a hide band on the 702's which at least at first, dug marks into my head after long periods of wearing (this still happens, but to a lesser extent now) which was genuinely physically uncomfortable. Despite the sleek form factor of the 550's head padding, it is comfortable for long periods of time surprisingly and even if not at the level of the Senn 580's it gives sufficient comfort for most of us to really have nothing to complain about.
Cable: I really do not care for people who spend almost as much on cables as they do on their headphones. The plastic around the cable of the 550's is thicker than that of the 702's and feels like it is of a much higher quality (the 702's cable really disappointed me since the start as it feels more cheap and flimsy, so I am just happy I have the ability to replace it). The 550's cable has to be good however, as it cannot be removed sadly, and time will tell whether this will be an issue if it is being bent about in a bag on the move or not...
Value: at £180 some may view these as expensive, but seeing as they are over £40 cheaper than the beats studio headphones (at least on Amazon), in my opinion more stylish, if not the most stylish portable closed headphones, with a crisper and more refined sound, and a superior soundstage there is a distinct realisation that for headphones of this quality, you really aren't paying too much, even if you paid the full rrp, which I find I can rarely say when it comes to AKG products. Maybe you won't like me comparing to the beats, as it is like beating on some child who has already had his lunch money taken, but I think that is who AKG are trying to compete with with this model. The AKG's are the Blackberry to Beats iPhone. One may be more subtle and won't go out of its way to part you with your money while the other will throw all the cheap gimmicks and celebrity backing and funding it has for advertisement in every mainstream music video you will see nowadays. I know what my preference is, and I'm sure that will be share by 90% of the community here also.
This is my first ever review of a pair of headphones, and I hope it is up to the high standards of these forums and I may well edit it as I use these more and more in the future.
Nice review! I actually think I might get some K550s after reading this, as I would need a more "silent" addition to the K601, since it is semi-open.
Great review! I am really considering these cans now.


Member of the Trade: rhythmdevils audio
Pros: Looks, Build Quality, Decent tonality and fairly flat FR from midrange down to bass, no treble emphasis, decent soundstage for a closed headphone
Cons: Serious peak and resonance in one spot in the upper mids ruins an otherwise decent headphone
First Impression
When I first listened to these headphones, my initial two thoughts in this order were:

1. Wow these sound pretty fast and also fairly even

- 15 seconds later -

2. Wow something is wrong with the upper mids
who cares
Build Quality/Aesthetics
These headphones feel very well built.  I can't speak to their longevity or durability, but they are nice to hold, feel sturdy, the movements are tensioned well and feel solid, there's no creaking of cheap plastic.  The finish feels durable and well made.  One of the better headphones out there IMO for it's apparent build quality and finish. 
They look very nice when sitting on your desk, and in pictures.  A good design, but they are one of those headphones whose looks don't entirely translate to looking good when worn.  They have all the right shapes and dimensions relative to each of the parts, but the whole thing is just too big to look very good.  For their size, I'd say they don't look too bad as they are slim, so they don't stick out horizontally very much and give you the alien mind probe look that grados and many closed headphones do.  The headband is slim too since it comes together at the top of the cups, so it doesn't have that gigantic and unnatractive arc that the older AKG's have like the K240.  The headband hugs the sides of your head well.  Still, the cups are huge even on my big noggin.
Very good except that the earpads just aren't thick/deep enough.  Huge design flaw IMO because everything else was done very well for an extremely comfortable headphone.  The cups swivel in a really nice way since they have a good amount of friction in the movement, so you can place them at the right angle for your head, and they stay there.  Headband is comfy and is the right shape.  But the earpads aren't thick enough to keep the grill over the drivers from hitting your ears.  With such huge, soft earpads this is a pretty big fail IMO.  I tried putting the foam donut shaped inserts that Hifiman has in their earpads into the K550 earpads, increasing the thickness, and it had no effect on the sound and made them supremely comfortable by simply increasing pad thickness.  So as long as you don't have huge ears they should be fine.  Or if you don't mind a little pressure from the grills.  it doesn't hurt too bad on my big ears, but it just would have been so easy to avoid this situation.  I get the feeling they didn't do much real world testing on these and got carried away with computer modeling. 
They overall have a flat, balanced sound from bass to midrange with good tonality, and with a treble presence that is in balance with that part of the spectrum, which is very rare for headphones.  But there is a serious problem spot in the upper mids that ruins this headphone.  A resonant peak in a small part of the upper mids.  I would describe their overall sound as a slight rainbow shape FR, though leaning upwards towards the upper mids for enhanced sense of clarity.  They also can sound kind of fast for a closed dynamic.  Not ortho or stat fast by any means, and not Grado fast, but maybe 6/10 for speed.  Not bad. 
Good not great.  It extends down plenty low, it seems flat, there's no apparent midbass hump, bass does not bleed into the midrange or vocals in the slightest but is also well integrated with the midrange.  There's no "bass + mids"  or subwoofer effect where the midrange and bass feel separated by gaps in the spectrum.  They have a cohesive transition from bass to mids, likely from a fairly flat FR.  But bass is a bit low in quantity despite what the FR measurements suggest.  The bass is in the background on these phones, with emphasis on the midrange.  Not for bassheads at all.  Bass is not bad quality, but it sounds kind of dry and a bit soft, whereas better headphones have more definition and dynamics and detail in the bass.  Not bothersome, especially since it's in the background.  I'd describe the bass as being just enough to provide a foundation and not sound too lite, but too low to sound totally neutral- it keeps your attention on the midrange.  It gets out of the way so to speak, for better or worse.
I'd say the treble on these is very similar to the bass.  Good not great.  There's no emphasis in the cymbal range as far as I can tell.  If anything it sounds a bit recessed in the upper treble.  Nothing sticks out at you here or is glaringly bad.  But the treble is not that clean or precise sounding.  It is a bit rough/textured or papery sounding.  Like the bass, I'd say it's a backdrop for the mids.  Not a treblehead headphone either.  Yet despite this lack of apparent brightness, these phones have a strong sense of clarity about them.  I think this is what people like in this phone.  They don't sound dull or rolled off or warm at all.  Likely because of the slight lowering of bass volume, along with the emphasis in the upper midrange, the "clarity" range in the FR.
Here's the problem.  Both the bass and treble on these are both presented as a backdrop for the midrange but there's a serious problem in this area, so these phones wind up failling short for bassheads, and treble heads, and then have issues in the midrange.  First the good part.
The heart of the midrange and the lower midrange is done pretty well.  Vocals have both the proper richness for a male voice like Tom Waits or Chis Isaak, which is surprisingly rare- they don't make vocals sound thin despite the lack of bass emphasis.  They also don't sound overly rich at all.  Chris Isaak's voice sounds very good.  Vocals also give the proper air and breadth to female vocals like Emmylou Harris or the Audiophile favorite Allision Krauss.  But sometimes vocals reach up into the problem spot and sound off. 
Upper Midrange Issues
There is a spot in the upper midrange that has a pretty bothersome resonant peak.  I kept wanting to call it "glare".  The upper midrange glare isn't the most peircing or painful I've heard in a headphone but it is very bothersome and might be described as severely "jarring".  It doesn't seem to cause me to reach for the volume knob as feverishly as some phones have, but it does keep me from turning them up and leaves me in a state of fear wondering when something is going to hit this problematic range and if it is going to hurt, since it seems to be right on the threshold.  Any instrument in that range sticks out way too loud, and looses proper tonality as the sound in that range gets mangled by resonance and takes on a plastic tonality. You can clearly hear the coloration being added to what should be the original signal.  This is partly because it's such a specific problem spot.  You can sometimes hear an instrument or voice go up in the range and suddenly jab at you by suddenly increasing in volume while taking on this plasticky resonant glare.  The decency of the lower part of the spectrum gives it a "surprise attack" quality which is what generates the fear and hesitancy when listening.  If there was an instrument that existed only in this range, I am doubtful you would be able to hear what instrument it was.  Some recordings play well with this problem spot and it's not grossly apparent because of the frequencies being excited by that recording and the particular balance of the recording (if the recording has a peak in that spot too, it's clearly going to be worse).  But even on these recordings, this spot gives the whole spectrum a cheap plastic headphone feel kind of layed over the sound, as if you are listening to some very good throw away headphones.  I kept thinking of them as the best airline headphones ever.  Much better extension, tonality, more flat, but still plastick-y. 
Overall good size for a closed headpone, has a spaciousness about it, but there's something strange about it as well.  It's almost like there are 2 soundstages happening at once, the lower part of the spectrum sounds more spacious to me than the upper mids/treble, which sounds more constricted.  This gives them a lack of coherency, or a kind of bad crossover effect, where the sound is a bit disjointed.  I think this is because the resonance artifact in the upper mids destroys soundstage by getting in the way of the "trick" the headphones are playing on your perception.  Soundstage is also destroyed by a "driver dildo" that was installed on the back of the driver creating a tiny chamber behind the driver rather than the comparatively larger size of the earcup.  I'm guessing it was placed there in an ill conceived attempt to control the bass, but I have modded a pair of these by removing this dongle, and correctly damping the cups, and the soundstage becomes more coherent. 
Good looking, sturdy closed headphone that is fairly comfortable and has a mostly well balanced, even sound except for a very problematic part of the upper mids that sticks out sorely and ruins them. However, this part may not bother everyone.  If it doesn't bother you ie if you're not sensitive to resonance or FR irregularities, and you are looking for a well balanced headphone erring on the side of being a bit basslite for the sake of clarity, and you want good soundstage these may be a good choice for you.  If you are not bothered by Grados you may not be bothered by this resonant peak.  however, Grados have much more natural tonality, for example vocals sound more life like.  I recently had an MS1 here and despite their colored signature they sound better than the K550 in every way except may soundstage width.  There's no plastic tonality in the MS1's signature. 
Here is a picture of the inside of the K550's cups.  The lack of damping here contributes to the resonant peak, but after spending time with my modded pair which has damped cups, I have found that it is also being caused by the driver itself.  Damping the cups helps, but doesn't fix the problem.  The small rubber thing in the middle of the light gray circle around the driver, is the "driver condom".  This seals around the driver and makes a small enclosure size behind it.  The light gray area are vents, though they seem to be closed off with solid plastic.

rhythmdevils, probably we have exact same pair of ears.
I bought k550 out of curiosity and everything you said about it is true. Returned it today.
Thank you.
Anyone who can get any pleasure from hearing high brass fanfares through these headphones is also likely to enjoy the sound of a dentist's drill gouging his teeth.
Spot on review right the way through, as I have experienced these headphones - I really wanted to like them, particularly in light of the build quality, but I keep finding myself touching the volume down to soften the mids, and the listening sessions never end up being that long.  Its a shame as they are beautifully constructed and designed :-/
Pros: Great sound, good isolation, extremely comfortable, neutral, good styling
Cons: rotate 90 degrees rather than 180, 3 meter cord is long for portable use.
I just picked these up today so this is just an initial assessment.  These are a great sounding headphone overall but the fact that they are also closed back and still have great soundstage at 300 bucks makes them well worth checking out.  These are very comfortable, and I don't have any problem getting a proper seal with them.  
The only things I have found that I would change about these in a future edition are: the earpieces rotate 90 degrees rather than 180, and the cord isn't detachable like it is on other AKG headphones in the price range.  The reason for wanting the earpieces to rotate 180 degrees is that with the way they are currently set up if you wear these around the neck and fold the earpads flat, as to get them out of the way, the pads are facing up and out rather than down.  If I end up talking to someone quick I like to lay the pads flat against my chest so I can talk to them without having them hear what I'm listening too.
The other thing is that the cable is not detachable although that in itself isn't really the issue for me.  For portable use it would also be helpful if these headphones had a short 4 foot cable but can understand why some people would want the longer 3 meter cable if they were using these for mixing and studio work.  Having a detachable cable would make it easy to pick up a second shorter cable or for them to be able to include it with the headphones. I imagine you could also do a talk through cable in the shorter version as well for people who look for that feature.
These are a great sounding pair of headphones whether you need the isolation of a closed back headphone or not and are well worth checking out.  These are a very revealing pair of headphones, there were parts of some Louis Armstrong recordings I listened to that I had noticed how much reverb there was on the vocals previously.  This was especially present when combined with my portable rig, 7th gen Ipod Classic and Fostex HP-P1, and a little less so on my desktop setup, mac pro and Headroom Desktop Amp.  These are by no means a bass heavy headphone and I would even go to say it is a bit recessed but only slightly.  The bass is very tight and well controlled.  This was something I really liked while listening to tracks by Massive attack. The vocals would seem to take center stage but over all a very neutral sound on these headphones.  The soundstage on them is very good, especially when you consider that these are a closed back headphone.  
I had originally gotten these to use more or less just with my portable setup but I like the sound on them enough that they will likely find there way onto my desk a fair amount as well.
You didn't say anything about the sound...
The part where you complained about the earpads not rotating enough... Ever heard of a pause? ;D That just didn't make any sense to me.
I understand what you meant, but I was just sort of confused by the reason. Though it's also more comfortable to have the drivers facing your chest I suppose.


500+ Head-Fier
Pros: looks good, sounds good
[size=x-small]first listening
Children of Sanchez, Chuck Mangione
CD1 Tr.4 enough space between drums

good fit on the head
very good shielding against environmental noise [/size]
[size=x-small]more coming soon[/size]
pics here

First hearing test
AKG K550 - AKG compared to Q701, K501, K271 MKII, Denon AH D7000
Source: Marantz SA 7001 KI
KH Amplifier: Green Solo (GSP Audio), WNA MKII (DIY, modified kit)

Headquarters: Q701 Earpads have larger diameter, K550 earpads slightly smaller inside diameter and feeling softener - could become a littel more warm during prolonged periods. The two listeners capsules, they can pull out each about 35 mm, good screening.

Very good shielding against environmental noise (better than the Denon AH D7000).
Good fit on the head.

Tues 20th Sept 2011
K550 after about 4 hours birning in

Test at the Green Solo (solo has 33 Ohm source resistance and the K550 feels better at the WNA MKII with 15 Ohm source.)

Pink Floyd Final Cut (Version with - "when the tigers broke free")
Track 1
K550 background sound - cars are nearer the as with Q701
Jingling of coins and finely resolved clearly audible - the Q701 would resolve this a bit finer.
Track 2
0:30 K550 the beat is more concise than in Q701
Track 3
The K550 sound stage seems a little closer than with Q701, which staggers a bit more extensive.
Q701 have a little more air between the instruments and singers.
Track 4, "When The Tigers Broke Free"
Q701 dry and deep bass, more air between instruments, they are sold more clearly.
Track 5
K550 voluminous, closer direct - Q701 dry deep bass, better resolution, more air between instruments.
Track 6
as above
Track 8
The impact of the grenade at the K550 sounds more real.

Magic of Himalayas, Mystical Scent
Track 01 Sacred Book
K550 deep, powerful bass (but not as extreme as that of the Denon AH-D7000)
Track 05, 07, 09 - as above

From now on WNA MKII
Karajan, Beethoven Smphonies No. 5 & ​​6, Berliner Philharmoniker, SACD
Here it was found that the K550, the lower source impedance (15 ohms at WNA MKII) and a little more power the amps are better pleases.
The two symphonies, I listened to without many cross-checks.
In the heights the K550 is apparently not up as far as the Denon AH D7000, with the latter, I could hear the noise of older recordings.
Comparisons of the frequency response curves would be a hit - if these curves were already online.

Chuck Mangione, Children of Sanchez
CD1 very realistic with the K550. Punchy bass.

Generally, the Q701 has a more distant, wider sound stage, the K550 closer, more direct.
The Q701 seems to resolves finer. When K550 in some passages I have a sneaking feeling that he colored a trace. But I might be mistaken as well. It just sounds different than the open-K501, K701, Q701. It just sounds different than the closed Denon AH D7000 too.
Do not ignore the price differences!

A cross-check to K271 MKII (nearly similar to K272HD) - the K550 sounds better than the K271 MKII.

A hearing test, like this, is always a subjective snapshot of a person, and, moreover, depends on the daily constitutional.
A real assignment and struggled even more with this point allocation (as do some HiFi magazine) is bringing into question.

To be continued.

Please excuse my bad english - I used Google translate and www.dict.cc - the original is written in german.
Hi Fritz, nice review so far. Please continue it. I placed a link to this review into the AKG K550 - NEW!! thread here on Head-Fi. Now this should get more attention.
Nice preliminary review, Fritz, thanks.