AKG K551SLV Closed-Back Reference-Class Headset with In-Line Microphone and Passive Noise Reduction, Black/Silver

Background:Not many reviewers mention their hearing capabilities before starting a review, I can hear up to 21kHz frequencies so I feel as if my ears are fit enough to make this comparison with some sort of authenticity. If you want to test your hearing I recommend you give yourself a test at: (edit: amazon doesn't allow links)I understand that music and headphones are a highly subjective topic, so I will state my sound signature preferences beforehand to give the reader an insight of where my words are coming from in this review. I prefer a neutral bass response, forward mid range, and slightly elevated treble. I am also not a particularly treble sensitive person.For over a month, I have used both the q701 and k551 with an external amp and DAC using 320 kbps and FLAC files. The music genres I listen to compose of metal, rock, classical, jazz, classical guitar, acoustic, and a little bit of indie. As you can see, I do not listen to music with tons of bass, so those looking for elevated bass should be warned beforehand that none of these offer exaggerated bass for modern EDM/pop/rap music. I chose specifically to review the q701 against the k551, as the k551 is often considered to be the closed alternative of the q701. I have yet to come across a full review between the two, so I though I'd give it a shot.Quick notes before I get started:-q701 is essentially a k701/702 with a slightly toned down treble and more bass-k550/k551 are essentially the same besides minor changes in the trebleDesign and build quilty:q701- The plastic/leather headband is extremely flexible and feels very durable. The glossy plastic design however, does look and feel kind of cheap in my opinion.k551- Unlike the q701, the k551 is made of metal and non-glossy plastics. It looks and feels very sleek and premium, the earcups can also swivel which can help with proper positioning.Comfort:q701- The velour earpads are deep, firm, and soft, but comes with strong clamping force that causes discomfort after using for a few hours. The top of the headband has bumps that are extremely uncomfortable and digs into your skull, I alleviated this problem by cutting away the bumps with a scalpel and covering it with some padding.k551- The earpads are leather and incredibly soft but very shallow (your ears will touch the driver). The clamping force is much lighter which prevents discomfort around the ears after hours of listening, but this does come at a cost of creating a pressure point on top of the head due to the extremely thin padding on the very hard metal headband.Bass/ mid bass:q701- Unlike what many people say, the q701 does NOT lack bass, this was only a problem on previous generations such as the k701. The bass is neutral and more than plentiful unless you are a basshead. The bass is very tight and quick with a very good mid bass to give fullness to the music.k551- The sub bass of the k551 is excellent, but there is not much else good to say after that; the rest of the bass spectrum falls short. Despite being closed back, the k551 is matched or surpassed by the q701 in every aspect of bass quality and quantity aside from sub bass, and sounds somewhat "tinny" in comparison to the q701 due to the lack of (in my opinion, recessed) mid bass. Deeper male vocals for example do not have much body and sound slightly sibilant. I understand the k551 needs a good seal for it's bass, but no matter how I wore them, bass levels remained the same. On an individual instrument note, bass guitar is much more audible on the q701 and drums sound a lot fuller and true to life on the q701.Mids/upper mids:q701- The q701 has a neutral midrange with very good detail and no mid bass bleed. Vocals have no sibilancy, but sound a bit distant due to the large soundstage. The upper mids do however have a sparkle which makes these great for female vocals and electric guitark551- The k551 has a more forward but slightly sibilant vocals combined with a smaller soundstage which sounds more intimate for vocal centered music. Electric guitar is also more forward, but are higher in pitch and do not sound as pleasant as on the q701. Piano on the other hand sounds extremely pleasant on both headphones and I would have to call it a tie in that regard.Treble:q701- Despite being classified as an "analytical" headphone, the treble is not overly emphasized and it reveals all the micro details while still sounding smooth in classical or electric guitar music. I do not get any treble fatigue after listening for hours.k551- The k551 is known for having "artificial/metallic" treble, and while I didn't notice it during first impressions, after comparing it with the q701 I would have to agree that the treble sounds somewhat metallic due to the artificially enhanced treble. The cymbals for example, are extremely prominent and harsh in rock and metal tracks and the tonality of electric guitar seems a bit off. Because of the elevated treble, I do get treble fatigue in listening sessions over an hour.Soundstage:q701- The q701 arguably has one of the largest soundstages in any headphone besides the likes of the hd800. The soundstage does has more width than depth, and the large soundstage can make vocals seem a bit distant at times. The huge soundstage makes classical music sound absolutely incredible on these; as if you were in a live performance.k551- The k551 sounds more like an open back headphone due to the rather impressively large soundstage which is partly why I proceeded to compare the two. It has less soundstage than the q701 which helps for vocals, but the soundstage does not sound as natural as the q701. This is probably a limitation of being a closed back headphone. Classical music on the k551, while sounding superb, did not have the same level of immersion and "wow" factor as on the q701.Imaging:q701- The q701 has very good imaging but is somewhat hindered by the fact that the soundstage has more width than depth. This makes the imaging not as precise and slightly "confused" sounding, this is only noticeable while nitpicking.k551- The k551 has a similarly good imaging as the q701, but has an edge where it is easier to distinguish because of the smaller soundstage and more treble.Instrument separation:q701- The instrument separation on the q701 is simply amazing and combined with the large soundstage makes it one of the best headphones for classical music.k551- Part of the reason why the treble is fatiguing on the k551 is because there is less layering and everything is just more forward. Although the k551 has a large soundstage, the instrument separation is not quite as good as the q701 and sounds slightly congested or less 3-dimensional in comparison. This is most noticeable in busy tracks with a lot of instruments such as metal, but the separation is still top tier for a closed back headphone.Isolation/leakage:q701- Because of the fully open design, the q701 does not isolate at all and leaks everything you listen to.k551- The k551 does not leak sound due to the closed design, but the isolation is only decent at best compared to some of my iems, and because of the elevated treble it could cause fatigue when you turn up the volume in a loud environmentAmping/portability:q701- Although the q701 does not require much voltage with only 62ohm, it does need a lot of current so an external amp is highly recommended.k551- The k551 is only 32 ohm and can be driven by mobile devices easily. The cable is not removable, but it does have volume controls which makes it a good choice for portable usage.Gaming:q701- The huge soundstage combined with the hyper revealing treble makes the q701 excellent for gaming and gives you an advantage in shooter games. The mid bass adds a nice fullness without bloating the other frequencies, but the treble does cause some fatigue over a few hours of gaming when there is a lot of gun action going on.k551- The k551's smaller soundstage with better imaging helps to pinpoint directions more precisely than the q701, but the elevated treble will cause fatigue much quicker than on the q701.Conclusion:Despite the k551 being considered a closed version of the q701, in my experience the two sound different enough to be two entirely different headphones for different sound preferences. The q701 generally has an edge over the k551 in most categories, but if you like very bright headphones and desire more intimate mids, then the k551 could be the better option along with it's portability benefits. I generally prefer the q701 for classical, jazz, metal, and electric guitar music. While I end up preferring the k551 for vocal centric music after I EQ down the upper trebles by 2-3dB.

If you do a review search of these cans online, and use the authentic sites where audio professionals who use and review gear for a living discuss equipment, you'll discover that these cans get 4.5 or 5 stars 98% of the time.Look, AKG designs their top end cans with a definite similar sound. And this sound is clinical, analytical, and transparent and detailed.....AKG "audiophile" phones, just like Beyerdynamics "audiophile" phones are created to let serious music lovers look deep inside the music and see the parts as if using a sonic microscope.... This is the intent of AKG higher end "audiophile phones, and that is the intent of THESE 551 phones, so, if you dont understand this, and are not familiar with what "audiophile" is all about, then you wont understand AKG or like many of their best sounding headphones.An Audiophile is a person who wants to hear their gear and also hear the music.They want to experience the forest but not at the expense of not being able to look at all the trees.They want both., and are not so interested in "does the bass response kick my eyeballs around", or, "these dont sound so good with RAP music or metal".Follow me?So, if you are looking to listen and not just listening to feel the beat, then the AKG products, the high end AKG product and the Beyer high end, and to a slightly lesser degree the Sennheiser high end, will let you look deep inside the music and allow you see what you are hearing....And if this is not what you are using headphones to do...which is., to look at the parts of the music you are hearing, then an Audiophile headphone like the K551 is going to be a big fat modestly expensive disappointment for you.

Maybe I'm out of my element since I'm mostly new to the professional-grade headphones thing, but these were pretty great until the buyer's remorse set in. They're very large on the ears (I have a slightly larger than average head) so you can't really go out with them. Can't really fold them to a portable size so really, they're meant for home use.Sound quality wise, they're great. I had a $40 pair of AKGs years ago and even they have quality sound so of course these are going to be great. No sound leak at decent volumes and no heavy bass to ruin natural sound. They even bring up details in music I hadn't noticed before for years.As with most other headphone remotes, it only works with Apple products, which was expected (I'm an Android user so eh). The thing that kept me buying this instead of the K550 was the mic but when I would make normal calls as I always did with my earbuds, the person at the other end would always complain I sounded too muffled, and it would only be fixed when holding the mic closer, which defeated the purpose.I was impressed with the quality but found that I'd have to force myself to use these instead of my $20 earbuds so I wouldn't waste the money I spent on them. They were too big and took up too much space to be convenient. I ended up selling mine and getting a pair of Bose earbuds in replacement, but that's a personal thing. Again, these have a great sound quality. But don't get them unless you want them for the right reasons. Tl;dr for the studio, not out of the house

Great clarity. Headbangers say not enough bass and sibilance in the highs because: 1) They want tons of bass (valid preference if that IS your preference); and 2) They are hearing their sources for the first time and the sibilance is in the source. So, if you are a headbanger, this is not your headphone and there are many other good choices for your headphones (and it's ok to be a headbanger). If you are not a headbanger and want music to reflect a sound closer to reality, then this IS your headphone. Very comfortable and non-sweaty for hours of wearing. Spread out sound stage like open-air headphones, but these are, of course, closed. One slight ding is that while the sound in the headphones is NOT audible to those around you, the ambient noise around you can be heard a bit, though quieter and muffled compared to sound without the headphones on. This means these don't suppress ambient noise as much as noise canceling headphones, but sound much better than noise canceling headphones. During very quiet musical passages, you may notice ambient noise. During passages at a conversational level or louder, you really won't. Other slight ding is that these are big and they don't collapse into a tiny space. I consider the great comfort and sound quality to be worth the slight trouble of carrying them.

I'm convinced the audio world has gone crazy. I've become a headphone connoisseur--or obsessive--and I've owned headphones from Bose, Beats, Audio Technica, Sennheiser, V-Moda, B&W, and PSB. No matter how they are hyped, I almost always notice a sound that veers heavily toward bass and a veiled "warmth". Either everyone is trying to copy Beats or they just assume everyone is listening to mp3's so why not create a sound that will camouflage the poor source quality?Enter AKG. They design headphones with seemingly no effort to artificially add bass or warmth but instead strive to create transparent, clear sound.And everyone bashes them for it.I have read endless complaints about how "bright" they are and "lacking in bass". These things just sound accurate and realistic. I think people have almost forgotten what that sounds like and--in the bizzzarro world we live in--AKG's true to life sound is what people's ears perceive as "weird". It's like The Matrix! But.....different.I say forget it. These sound drop dead amazing and all the others sound dull and lifeless (to me) by comparison.Just don't listen to mp3's with these babies. That might hurt. I listen to CD's ripped as WAV files on my iPod and I couldn't be happier.