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AKG K550 - Review

Before I dive in to my bulk DAC & headphone amplifier tests I wanted to squeeze in one more headphone review so next up is the K550, AKG's latest reference headphone. I am trying something new with my photography to make it feel a bit more 'clean' but enough about that, on with the review...

Up until recently AKG's reference '7 series' headphones (K701, K702, Q701) have followed a nearly identical design and have been very open with almost no isolation. The K550 breaks this tradition in many ways bringing a complete redesign to the table, inside and out. They also have decent isolation with a closed back design that's easier to drive and has even greater comfort. The gargantuan size remains but the price tag has been substantially reduced (half the RRP of the Q701). It's fundamentally different and at the same time it aims to keep the same AKG reference sound.


One thing that really impressed me when I picked up the AKG Q701 was the wonderfully crisp sound. They have the ability to present detail with such transparency you couldn't possibly call it dull. Tracks that have a good amount of detail are presented with a crispness and sparkle that's addictive if at times a little artificial. With the K550 that lovely detail throughout the frequency range is still there but it's slightly subdued and feels more natural.

As long as volumes stay reasonable the midrange is beautifully rendered, if not sibilance tends to creep in rather quickly. Vocals are engaging, textured and fun. The soundstage is really great all round too, similar to the detail it's less 'in your face' compared to the '7 series' but feels more three-dimensional as a result. As well as good left/right staging there is good depth too which for a closed back headphone is really quite impressive. 

You might expect the closed back sound characteristic muddying down and plumping up the lower frequencies but that's far from the case here. It seems AKG have tried very hard to avoid this problem but in doing so they have made a sound that can feel devoid of body. Low frequencies are full of detail but can feel recessed compared to an average presentation (or even other reference headphones). Searching for this body with volume means they get drowned out by everything higher up in the range due to a harsh sounding treble. The bass can feel so lean in some tracks that it sounds artificial and brings a veil to the sound that is unusual for a product in this price range. This lack of body is accentuated in noisy environments too.

Pressing the cups closer to your head seems to alleviate the issue somewhat. The seal with the pleather is not strong enough largely due to a lack of clamping force but the main issue seems to be the location of the drivers so perhaps modifying the headphone could help. Modifying equalisation with either software or hardware can help a little but pushed far enough to make a difference and sound quality suffers. If you are partial to powerful depth and kick to your music you will struggle to enjoy the benefits that this sound has to offer but benefits it does have.


The 32 ohm impedance of the K550 is lower than the open back '7 series'. This make it easier to drive directly from portable media players. Impressively this seems true of the crisp detail but less so of the volume levels. Running it from the Samsung Galaxy S and iPhone 4 mobiles the volume seemed pretty the same as AKG's '7 series'. The Galaxy S feeling just about loud enough at 100% volume and the iPhone 4 at about 80%.The iPhone 4 showed a good deal of detail but the brighter presentation made the treble harsh. The Samung Galaxy S didn't have enough volume to let the high frequencies become much of a problem but it's a much more dull presentation anyway. This dullness actually worked well, bringing in a bit of weight to the lower frequencies while the headphones overall texture remained intact enough to make an enjoyable sound.

Running the K550 from a computer directly (on-board soundcard) provided very little volume, even less than from the Samsung mobile (which is very unusual, especially for such a low impedance). More predictable was the rather lacklustre detail which rather destroyed the strengths that the K550's bring to the table.

Running the K550 from the portable Fiio E17 DAC/amplifier connected to a computer did increase the bass a little. The bass boost feature of the E17 did improve the general lack of body a little, but it's not enough to bring it close to other great headphones at this price. Pushing the troublesome treble down after a volume boost was less successful - destroying the sound much quicker than with a bass boost. More detail emerged with the E17 across the board but most other headphones get a bigger boost with this machine. Moving up to the Audinst HUD MX-1 DAC/amplifier brought in a nicer and larger amount of detail as well as bass (compared to the Fiio E17 with no boost). This was the best audio performance source for these headphones, even beating the considerably more expensive Yulong D100 mkII.


Despite the fact that I find the K550 rather lacking in body not everyone will share this view, so I try to remain objective here more than any other section. I did find it's presentation awkward with dubstep, hip-hop or heavy / industrial music but at the same time a lot of it's strengths brought out some really nice sounds from music.


  • 'Bells Of' by Noisia starts off sounding so crisp and articulate with it's high pitched notes. Because of the dynamic nature of the track, when the bass does come in, doesn't sound too recessed and this is very enjoyable. As the track increases pace the bass starts to kick and here it suffers a little for with a veiled low end but if you are living with this sound as your only presentation you will thoroughly enjoy this a lot and probably wonder what I am complaining about with this lack of power and body. Move to another track by Noisia like 'Alpha Centauri - Excision & Datsik remix' however and if you think this track has energy and power here you need to hear it on another set of headphones. Audio Technica ATH-M50's or VModa Crossfade M80's are not exactly bass head 'Beats' headphones but on those two this track will blow your head clean off.

  • 'Gold Cobra' by Limp Bizkit showed some really nice features like great pace, separation, soundstage, detailed midrange and felt really enjoyable. It didn't even seem to suffer too much for the lack of body for an energetic track, actually the only negativity here is that when the volume is up to enjoyable levels the symbols displayed as annoyingly sibilant most of the time (also true of the whole album).

  • 'Foc' by Rodrigo Y Gabriela, with it's fast paced acoustic guitar, felt wonderfully bright, crisp and largely enjoyable but definitely lacking in body. Their music often gets a lot of thrills from the hard strumming of the strings and thumping of the guitars (possibly due to their heavy metal roots) but the only enjoyable elements here are in the midrange or above. 

  • 'Kids With Guns' by Gorillaz starts off sounding like there is no problem with bass presentation, until you test it on another pair of headphones that is and then it feels bloated but I think this is more of a fault of the track rather than with other headphones bloating the bass too much. 

  • Mozart's piano concerto No. 21 in C major by the Ljubljana Symphony Orchestra displays great instrument separation with amazing clarity and texture. It's a rather subdued classical track and sounds great but more energetic classical pieces can bring in the veil due to the lack of low frequency power some times.

  • 'It's a kind of Magic' by Queen has some wonderfully clear and brightly presentation vocals. Listening to the opening of 'We Will Rock You' feels like you can count the amount of people clapping because it's so delicately textured. Most of Queen's 'Greatest Hits' album has a really nicely texture, great instrument separation and a surprisingly three dimensional soundstage.


As mentioned a little above the K550's sound feels similar to open back '7 series' despite the closed back / isolation and this is impressive. The crisp detail is still present on the K550 and even sounds more natural. Although the midrange and soundstage is more impressive there is a veiled impression with the K550 that is not found on the '7 series'. It's something that's more realistically reproduced on other reference headphones including AKG's own '7 series'. The comfort of the K550 is better than the '7 series' mostly because it has a much nicer headband cushion. The clamping force has been reduced for the K550 but this not wholly a positive aspect. It makes the cup cushions difficult to press in the right areas and get a good seal for the isolation. This contributes to the lack of body but is not the sole reason for it.

The Beyerdynamic DT770 Pro is another good example of a closed back reference headphone and there are obvious similarities here. I did find the bass a little lacking on the DT770 at first too but it opened up over time and I was left with a really nice feeling of texture that isn't quite present with the K550. I also felt the DT770 slightly veiled and although this never went away it was something that I could live with much more easily than with the K550's. Higher frequencies felt much less grating at higher volumes with the DT770 but the trade off here is that crisp detail which does feel more present on the K550. Isolation and comfort on the DT770 is better than the K550 despite a slightly overzealous clamping force.

Although the Sennheiser HD800 is an open back headphone I mention it here because of the 'reference' tag that it shares with the K550. Being four times the cost this is completely unfair but I bring it in to the review because this to me is how a reference sound should be. It neither felt lacking in bass or veiled like the K550 does. This shows what you are having to compromise on at this price point to get the 'reference' sound in a closed environment. Perhaps this is a technical limitation of the closed back design which is fine but it wont work for everyone.


The design of these headphones is really quite stunning. I am really impressed that AKG have come up with visuals quite so slick and striking after such a long reign with the '7 series' family (and even before that). The various shades of matte grey have lovely textures and a great mix of hard edges and sweeping curves. Also the amount of metal used here is great.


The build quality seems almost as impressive as the looks. The adjustable headband is simple and nicer than the self adjusting version from the '7 series'. The numbered notches in each side to keep it even are a nice touch and the cups rotate so they can be stored in a flat position. With very soft pleather cups and a spongy underside to the headband everything that touches the wearer is nicely padded. The weight is low for such a large design and the overall comfort is good. As mentioned before the clamping force to these headphones is very low and I feel this has negative side effects for the sound not so much for isolation but mainly driver position and body to the sound. Despite their huge size the hole inside the pleather ear cushions don't have very much room for your ears, no matter how hard I try I can't position them so my ears aren't touched by part of the cushioning which seems rather an odd design decision.

The lack of a removable cable seems a shame given that the later models from the '7 series' have the feature. The cable is fairly thick but it's standard AKG sticky rubber and 3m long (considering it's geared well for portable use) so tends to get bunched up in a mess easily. The 6.35mm (1/4") adaptor unscrews to show a 3.5mm (1/8") connector underneath and is designed just as nicely as the rest of the headphone.


The K550 is an impressive headphone that more than does justice to it's open back cousins but there are a few caveats holding it back from being truly stunning. An emphasis on comfort more than fit proves awkward for isolation. This accentuates a lack of bass body and searching for it displays and a tendency for harsh treble. For me other reference headphones are more appealing due to better all-round performance but if the shortcomings don't put you off you will truly love what it has to offer. Not much can compete with it's three dimensional soundstage and abundantly clear detail at this price. Here more than ever a thorough test before purchasing is encouraged.

Posted 10th June 2012

by Edd

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