Sennheiser HD 558

My thoughts on the Sennheiser 558
 
First, off, I would like to begin with the standard "I am not an audiophile" disclaimer.
 
The package came from Dahmart and on time - within 2 days of ordering with expedited shipping. The headphones were in mint condition but without the box. As I looked at them it became increasingly harder not to plug them in, and so I did. Thus starting my first lesson in "enthusiast grade" headphones. In the coming week I would learn a lot about the headphones I had ordered, sound signatures, and the kind of sound I was after.
 
Believe me, I spent hours scouring the internet for information on the 558, and there is plenty of it. And so far I have yet to find a review that truly shows the Sennheiser 558 for what they are. I stumbled upon threads about how to do the foam mod to make them sound like the 598, claims that they have the "Sennheiser veil", claims they are absolutely amazing, and claims they are over-rated. Lets sort through it all and dive into the HD 558.
 
When I put them on they were easily the most comfortable headphones I have worn, then I listened to them. One word comes to mind when I think of the first time I heard them: underwhelmed. I had a playlist of different music to try with them when I first got them. There was no aggression to the music, the bass was too polite (read passive and recessed), and I didn't feel engaged by the music. I close my eyes actively searching for qualities above my old headphones, a year old pair of Sennheiser HD202s. And there was. As I focused on the music I noticed the lyrics easier to hear and understand, and presented more harmoniously with the instruments. I try hard to imagine I am listening to a live concert, as I have read they sound like, but it doesn't work for me. They do sound more "outside my head" than closed headphones, but only just. If you try really hard you can try to convince yourself that the music is playing in the room, but even that takes effort. By this time I am frightened about my purchase. Within 15 minutes I desperately perform "foam mod" surgery on only the left side, and wore them for 20 minutes to see if I could tell a difference. I liked the results, it seemed to enhance what I then perceived to be the strengths of the headphones. They sounded a little more airy and detailed - although the bass seemed to take even more of a backseat it was amazing for some genres (Inception soundtrack comes to mind). I took the other one off and stuck the foam pads onto the top of a CD in one of those cylindrical plastic blank CD packages and put the lid on to keep dust out. I then proceeded to leave them running even when I wasn't listening to them in case they needed to "burn in".
 
By this time I was truly worried that I had made the wrong purchase. I checked the Dahmart return policy, which sucks by the way. They will gladly take any return for a 20% restocking fee. I wasn't about go for that. I tested my Sennheiser 202 again, and then it happened. They sounded sloppy, unrefined. The bass was boomy and didn't seem to know its place. It would impede on the other sounds. The vocals were not as clear. I realized then that what I first recognized as "lack of bass" was not a lack of anything. The bass on the 558 simply knows its place and isn't loose at all, it's tight and smooth; something I knew nothing about before I put on the 558's. In fact, the bass on the 558 is every bit as powerful as the HD202 - even with the foam mod. I spoke with StreetDragon and we shared thoughts about them. We largely agree the they are not in-you-face engaging, but they have a very musical, beautiful sound. He was kind enough to share some of his equalizer settings with me to bring out certain qualities that may be lacking for some kinds of music, like electronica. I am starting to realize that I might be a "basshead" due to what I want out of a headphone. I wanted a headphone that was clear, with prominent mids, and quality bass, and that's what I got, but the saying "be careful what you wish for" was prominent in my mind. The headphones were by no means bad, but not what I was expecting.
 
Fast forward 1 week of nearly constant listening....
 
 
I'm not sure if it's me or the headphones, but they sound better every day. Fuller, more detailed, more engaging. I don't know if I believe in burn-in, but the sound I get from them is different than it was when I first got them. I am accepting them for what they are, and what they aren't. They are good at most any kind of music with even with a flat EQ. They excel at music that is less aggressive and less dense. They seem to do best with laid back music. They are somewhat revealing, some music sounds bad due to sloppy mixing (read 50 cent "get rich or die trying" as a prime example). But, keep in mind no genre fails with these. If you have a hardware based EQ you should be able to make them sing with just about anything. With the EQ set as flat is a good way to start - these headphones are very mellow with a flat setting. I keep thinking about the "veil" because they sound very warm with some sacrifice to highs, but you can remove the veil easily with a simple EQ tweak.
 
Fast forward to today...
 
The headphones are getting warmer and warmer. I notice some of the otherwise great bass control in some songs, and I realize it's time to put the foam back on. I perform the necessary surgery, and find that the foam I put onto the CD has become very much fused to the surface. I had to be very careful not to tear the foam on account of how stuck it had become to the CD. Once again I did the mod only to one side (right this time), and I liked what I heard. The sound was more forward - more aggressive. The bass cleaned up and gained additional punch. The sound stage closed up a little, and it lost some of that "airy" quality it had. I whole heartedly agree with the opinion of a poster from another forum that the mod doesn't make it sound better, just different. As much as I would like to think that Sennheiser purposely crippled the 558's with the foam because it uses the same drivers as the 598, I'm not so sure that is the case. I'm taking the "Sennheiser knows best" route, and leaving them in for the time being. The undoing the mod makes them more up front and engaging. It almost seems like the mod tries to make the headphones be something they are not. I would suggest everybody who has a pair try them with the foam again if you have taken it out.
 
Conclusion -
 
If you have read this whole post, I hope it was enjoyable and worth while. Now for a word on my rating scale: I don't rate on a curve. If the ratings seem low to you it's because I'm not rating them for their price, I am rating them for the criteria and the criteria only. I have seen $20 headphones get 10/10 and 5/5, I feel that reflects off the fact that they only cost $20, and I save the value rating for the value rating. So, without further ado, here it is:
 
Comfort 9/10 - The plush earcups and headband are great, they don't heat my ears up, and even my wife who thinks expensive headphones are a total waste of money gave a nod of approval and wanted to know more about them. They clamp ever so slightly on the firm side, but are very stable on my head. I don't think there is any combinations of movements I could do to knock them off save using my hands. I can wear them with glasses and/or a beanie without problems. Very nice.
 
Sound 7.5/10 - I am rating these on what they are, not what I think they should be. After almost 2 weeks of listening for hours every day I know what these are about, and they are quite good at what they do. The 558 includes listeners of classical, jazz, new age, etc. In fact, I would say they are geared slightly toward those listeners, as the sound is designed to be beautiful and relaxing, not aggressive and adrenaline-inducing. The 558 can be poured into just about any mold and successfully thrive with some EQ tweaking, but it seems to prefer to be mellow. If you listen to rock, techno and rap, and want a sound that makes the hair on the back of your neck stand on end, there are probably better choices depending on the sound you are after because they lack what I will call the adrenaline element. Like I said, they are mellow and beautiful - you may be inclined to sway back and forth (as I frequently do) and hold your lighter high during some live performances because they are capable of truly making music sing, picky as they may be, as they are uniformly good, but every once in a while they make me pause and close my eyes to savor the sound. They are an easy 8 when in their element, a 6.5 or 7 for some fast, dense, heavy music.
 
***IMPORTANT*** Source is a Xonar DGX internal sound card streaming 320kbps music from the subscription service MOG. My opinions are based on this source.
 
Value 5/10 - I'm giving this a 5 for one reason: I bought them for $115 shipped, but I am assuming that the reader will pay the full price of $179. For just over $100 I am very happy with them and would gladly give them an 8 star rating. If I had paid full price for these I would feel like my money could been better spent. If you can get them for under $120 shipped then go for it, but if you are thinking about paying $179 for them I would make good and sure that you know what you are looking for in a headphone.
 
 

When I first listened to this headphone I was disapointed with how it sounds. Frequencies close to 150Hz are elevated and the trebles are damped. That results in a boomy sound as if I had a piece of thick cloth between my ears and the headphone. I removed the pieces of foam inside of the HD 558 but it improved the sound only marginally.
 
However once I played around with the bass and treble knob the sound of the HD 558 became more pleasing to my ears. I have never listened to music with a headphone before where I lowered the bass and raised the treble significantly. Only on very bright recordings like 80s pop & rock I found the headphone to sound about right.
 
Soundstage is an often used term in this forum. The HD 558 lets me localize instruments with a higher accuracy than I ever experienced it before. Sometimes it feels like I could grab the sound. A lovely feature that helps to improve the general listening experience is that I can feel vibrations on my earlobes.
 
If you have wide head these headphones would certainly feel tight. But the cushions are soft and the headphone feels comfortable. I even forget that I am wearing them. Over time cushions get dirty. They can be replaced. You have to pull quite hard on them before they let go. Putting them back on is a bit tricky. The headband can be replaced too. It is held in place with double sided adhesive tape.
 
The cable is only on one side. I like that. It can be removed but I haven’t seen any replacements for it. The connector on the headphone is a 2,5mm plug. On the other end it is a 6,35mm plug. An adapter is included. However it connects directly to the plug without a piece of cable in between. Very dangerous. You don’t want to stumble over the cable.

The HD558 is one of those headphones that even when you're not specifically listening to music, some soundtrack might randomly come up in a show or whatever and you catch yourself thinking gosh that sounds so nice. And that is not something that goes without saying, even with expensive headphones. Sometimes audiophiles may get in a habit of setting up their circumstances for listening to music: it needs to be this or that track or otherwise my gear just shows the problems in the recordings etc. None of that with these. These simply sound really nice upfront and they're a solid all-rounder too, although I'd have to say their particular "main skill" has to be vocals, just really good. I was listening to Blind by Korn a few days back and the growls came through beautifully. But it just catches you in general, there is no sibilance and it's noticably pleasant whenever someone starts singing, or even talking for that matter. I also like the stronger bass that these offer over the HD598. I've seen some people say that these are boomy, but I disagree. The way I see it there are two kinds of people: the one that needs to have that warmth in the midbass for the sound to be 'right' and those that want clarity above all. If you're in the latter group, then there are many other options that will suit you better than this. The bass sounds good to my ears, although you shouldn't be expecting super deep bass. A very good kick, but the bass is not blowing through the mids or anything like that at all. It's only the treble that can occasionally be a bit much for my tastes, but usually it's all good without any EQ. These are mostly dark and warm sounding, but they seem to have a bit of a surprising bright tilt to them that sometimes shows up out of nowhere. The comfort is probably the best out of all over-ears I've used. They're better than the HD598 and 599SE because those have a headband with pleather that tends to slide around on your head. The 558 has a thick layer of velour that is super soft and keeps the phones in place. I have average ears and the pads are big enough for me.

Recommended! Try to pick up a used pair while these can still be found in the wild. Even if it's just for podcasts or watching youtube videos, I can't think of a headphone more suited. I can't rate these higher than four stars because alternatives such as the DT770 and HD58X have a significantly more high-end sound to offer at very fair prices, but still, I really like the HD558.

I wrote a review a few years ago but I was new to the hobby then and so the review was not very good. Here is my updated review:

Before buying the HD558's, I was listening to music on some pretty mediocre noise-canceling headphones by JVC that I think go for around $50. But I liked them, because they had a very present mid-bass that, to me, made music seem very grounded and present. So when my 558's finally came, I was shocked that the music remained grounded in the mid-bass region while seemingly expanding in all directions in the higher frequencies. This was my first taste of what a good soundstage is like, and I was impressed, to say the least. Eventually, I lost the 558's, as I tend to do, but they were my daily drivers for something like 5 years. When it came to getting a replacement, I picked the 599's, because they seemed like they would offer everything the 558 did, but more detailed, more spacious, and faster. This was not the case. I'm not particularly a fan of the 599, so I thought maybe my tastes had changed and upon coming back to the 558 I would find the sound equally unfavorable. But, no, I didn't. I still like the 558 a lot, I find. And here are my findings, but I don't have a unit on hand, so this is mainly as I remember them:

Bass: The bass is still definitely the weak part of the equation here. They have been classified by many people here as bass-light, and I'm not sure exactly where that comes from, because to me they seem very heavy on the mid-bass, while not offering great extension. As a result, the bass is often quite boomy, and always very present, to a fault. I ended up finally getting relatively annoyed by the bass, but it was never enough to drive me to actually dislike the headphones; it made up for it in other ways, let's say. Just know that if boomy bass bothers you, these headphones might present an issue to you there. And it's relatively slow, too.

Mids: Mids on these are warm, smooth, forgiving, not terribly forward, although not recessed either. I can't find fault with the mids; they are dark, for sure, which I don't mind, but don't be looking for a huge amount of mid presence or forwardness here. It's just very warm - what more can I say? I wouldn't call them milky, or creamy, or anything like that; they are a little too distant for terms like that. But it's that distance that makes them so enveloping, like a warm hug. That's what you're getting from the 558's, and that's where they excel.

Treble: Veiled? Maybe. But the treble is not the focus here by any means. It's serviceable, it's not slow, it's not intrusive in any way, it's there just enough to bring out a little detail, but it definitely takes a backseat to other aspects of the headphones. As I recall, I couldn't really find any issues here. The 599 is a headphone that is similar to the 558 in some ways, except with much more forward treble / upper mids, and that doesn't work for me at all, so I would say that the 558 does the treble ideally for what it is.

Soundstage: Of course, upon first listen, the soundstage blew me away. If you're coming from cheap closed-backs (or really anything under $200 except maybe the DT770), it will probably blow you away, too. Now that I own the K712 I'm sure that the soundstage would seem more intimate than it seemed initially to me, but because the sound is so relaxed, I found that it ended up sounding very spacious anyway.

Build, comfort, etc.: They are very comfortable, if a bit clampy, as others have pointed out. They were never too clampy for me. The earpads are very nice. It was built well enough that I never felt like there were any issues, and they never broke, so that's good. However, I will say that I was not at all a fan of the cable they came with, and ended up having to replace it. The fact that they only give you a 1/4 inch connector is...what? For a while, I was using it with the extremely unwieldy 3.5mm attachment, and some carelessness ended up destroying my computer's audio jack. Probably factor a replacement cable into your potential costs.

A note: The foam mod that turns these into 598's, as people claim, is not to be trusted. When I did it, it made the bass much, much worse in exchange for an almost imperceptible gain in treble detail, which is again not even the point of these headphones. It's very easy to do, so I can't blame you for trying, but if you need the extra detail so badly, you really should not be buying these headphones.

Amp requirements: They do not need an amp. I never owned an amp while using them. However, I do recall one time that I went to the library to listen to a record (yeah, they had record players in the library), and fed through an amp the record I was listening to sounded almost unbelievably fantastic. That's about all I can say about that.

Overall impressions: This is an important pair of headphones for me, and I may very well get another pair at some point. I can't say that they're perfect, but since they're being sold for around $80 at this point, they perform extremely well for the price point, provided you're OK with the particular sound signature they provide. I am. I like these headphones; really the only thing that bothered me was the bass. If you are looking for a relaxed pair of headphones that will provide a comfortable, pleasant music-listening experience while still maintaining a good overall sonic balance and a fairly spacious, natural presentation, look no further (well, OK, look no further if this fits your budget).

Sennheiser has recently refreshed its audiophile range of with the HD518, 558 & 598 and the fabulous HD600 is almost out leaving just the HD650. This review takes a look at the mid-tier Sennheiser HD 558, which actually turned out to be the best value headphone in the current line-up.

Sennheiser HD558

The Sennheiser HD558 maintains the classic headphone look with good styling. I specially mention the “classic headphone” look because with the HD 598 Sennheiser has tried a new look/color which seems to have many complaining. Personally, the HD598 is a refreshing redesign and I have no complaints. Incase you are not the consumer who goes for the European sports car look (of the HD598) then its just one more reason to pickup the HD558. The new audiophile line also sports detachable cables, a welcome feature – as more often than not the cables are more susceptible to usage.The clean curves and bold looks and reasonably good plastic housing makes it worth the price. You can always look up the feature list on on the HD 558 product page, so let’s get on with things that matter more… (in my opinion).

The classic comfort that one expects from Sennheiser headphones is prominent the HD 558 and one feels it the moment the phones go on the head. The most obvious characteristic that you’ll notice with the 558 is the large soundstage and airy presentation (within this price category). Ofcourse one expects such a presentation from open-headphones in general, however I think that the 558s provide a good dimensional presentation for an entry-level audiophile headphone. I haven’t heard the Grados and Audio Technicas so I can’t compare them but I have heard the Sennheiser HD600 and AKG K550 and know a good presentation when I hear one! I tried out the 558s on both a Matrix Mstage followed by a Burson HA160 and the headphones stepped up their act with better resolution and dynamics.

Sounds like…

The highs were initially a bit shiny for my tastes but with time they did settle down. In general the highs are crisp and clean (probably my Cambridge DAC Magic rubbed off some of its upper end shine).The mids are lovely and smooth, right there along with both highs and lows. If you enjoy jazz and vocals you’ll appreciate the tone of the mids greatly. It definitely stands up in comparison to my previous Sennheiser HD448 (and it should considering the price difference, and it definitely would be the recommended upgrade from the 448s). Bass is in sufficient quantity for non-bass heads, though it does get slightly boomy when extending further down, all-in-all quite good for the price and I did notice slight betterment with burn-in (I recommend atleast 50 hrs of burn-in). I have been recently listening to a HiFiman HE500 and a Sennheiser HD650, so its very much likely that I have been “spoiled” with regard to the quality of bass that I expect . That said, I would definitely rate the treble performance of the 558’s higher than its bass.The HD558 retains most of the laid-back style house sound of Sennheiser which goes very well with a lot of listeners but if you are a serious rock and electronica nut these may not provide that pace or “zing” that adds a great feeling to such tracks. Though I cannot exactly pin down the flavor in the HD558, I see it as a more “popular” deviation from the previous HD6xx line. The HD558 is not as laid back as the previous generation of Senns, and I don’t see that as a disadvantage – it probably reflects the fact that Sennheiser is updating it’s house style with a bit of popular music listening styles. Overall the HD558 can be described as a very pleasant and slightly colored listening experience. The coloring keeps the 558 from getting cold and yet not too warm. This nature keeps the HD558 suitable for most music genres though hip-hop listeners may notice the lack of strong bass.

Sennheiser mentions that the 558 plays well with most mp3 players and portable media players owing to its higher sensitivity. I found this to be the case as the everything from my iPod Classic, iPhone to the Sandisk Clip could drive the 558 easily to loud volumes, that said the 558 ships with a quarter-inch headphone pin and using the provided 3.5mm adapter is quite “dorky”! Though Sennheiser says the sensitive 50 ohm HD558 is compatible with most portable audio sources, frankly driving it from mp3 players and laptop audio output sources is not a great idea. These headphones are meant to be driven atleast from a home audio receiver but one can also opt for a much more wallet friendly and portable headphone amp like the Fiio E10 and enjoy better sound from the headphones.

Sennheiser HD558 headphones

in conclusion…

The general pricing difference between the 3 models (HD518, 558 & 598) are roughly 30 bucks (HD518-100, HD558-130 & HD598-160).Remember that there is the HD518 which sits below the 558 coming in just at or under 100 bucks, my advice is to skip it! The price difference between the 518s & 558s is almost negligible…just hunt for good offers on the 558 (online) and you will definitely be coming away with a great value purchase for your money. The next step-up model HD598 is relatively pricier than the 558 in the real world, it goes without saying that if you are getting a good price on the 598s, don’t think twice!

My chain: Lossless -> Foobar 2k -> HifimeDIY Sabre DAC -> E11
 
The HD558 are doing it for me right now. I was not blown away, but they really don't do anything wrong. The bass is not boomy but does bleed a tad, not ideal for classical but it's not hugely problematic.
 
The mids are nice. Never overly resonant, just enough bite to give realism but not intrusive. Imaging is very nice, but transients are a little weak.
 
Having started my hifi game at IEMs and gone far enough to see the kind of soundstage they are capable of (TF10, SM3), and opting for my first real can to be closed yet with a good stage (DT770), I feel like I can really discern the elements of sound presentation that are unique to open headphones, and they are well-present in the 558s. The sound is not necessarily much "bigger" than my DT770 in terms of the size of the stage or how far away certain sounds are; the DT770 actually wins out on this in some cases, especially with certain types of electronic music (psytrance in particular). However the benefit of the open sound is literally the dimensionality of the sound: the individual "sounds" themselves actually have distinct dimensionality and spacial presence of their own, rather than simply being placed at relative distances to each other. It improves the actual realism of the sound and makes it sound more speaker-like or even "live" sounding. 
 
Timbre and decay are both superior to any phones I have owned; the warmth is obvious, and I can hear the "Sennheiser veil," but it doesn't really interfere with detail or realism when you listen closely. It is more noticeable with some music than others; it makes violins and pianos sound a bit veiled, meaning these are not the BEST cans for classical, but they are VERY far from the worst; again better than anything else I own.
 
These guys really show their strengths with music that combines synthesized and analog sounds, like Lindsey Sterling and Massive Attack. They give a very pleasant fullness to instruments and never let synthesized bass drown out real instruments, isolating everything neatly without giving that slightly artificial separation that some multi-BA earphones can showcase.
 
I will say that I personally I wish I had thrown in the extra $80 and gone with the HD598; I would like a little more upper midrange presence out of these guys, and the bass could be tighter. However that doesn't detract from the fact that these are definitely quality cans, they make a great compliment to my DT770 for when I want a more laid-back listen. Overall the sound is laid back yet involving, almost seductive; it doesn't have tons of punch in the bass, so some electronic like Justice or other dubsteppy-like stuff is underwhelming (my DT770s are better suited there) but more intricate, atmospheric stuff like psychill, Lindsey Sterling, later Simon Posford stuff (Shpongle, Younger Brother) is very involving. Even deeper house like Deadmau5 and Jackbeats is good. It can't quite keep up with some of the faster, super-intricate Shpongle tracks (I found the album Nothing Lasts...but Nothing is Lost more problematic than the rest), but then the only thing I've yet heard that can is the SM3, which handled anything I ever threw at it.
 
Overall I am happy with my purchase, these make a great compliment to my LEs; now to complete my mid-fi conquest I am going after something fast and aggressive with tight, extended bass, maybe a Grado? Perhaps HD25-i-II...any recommendations? ^_^

Note that my impression is with the foam removed from behind the grills.
 
HD558 is a very good headphone that I would recommend to everyone to listen to. Easy to listen to, not offensive sounding or dark sounding. Good price.
 
No amp required.
 
I have had the HD25-II before and the HD558 excels in every aspect except in the bass region.
 
Comfort: Pads could be softer, feels noticeably firmer than the pads on a ATH AD900X. Weight is ~260g which is not very light nor heavy, similar to that of the AD900X. Low clamping force. There is a little bulge on the rear side of the inner cups that may touch your ear creating discomfort over long listening sessions but should be fine for most people with flatter ears. Coming from Grado, this is noticeably more comfortable but not as comfortable as my AD900X mainly due to the pads' softness and the steeper angled drivers. HD600 and higher pads are noticeable softer. The pads collect lint quite easily. Acceptable comfort.
 
Highs: Does not stand out; does not irritate. Not the loudness nor does it have that sparkle a AD900X does. Cymbal shimmers are not as clear or obvious as on my Grado SR325 or AD900X. I don't think anyone who listens to classical a lot will enjoy these headphones. Highs do not try to grab your attention, not very extended. The highs suit others genres quite well as they are not offending. The highs combined with the forward midrange makes this headphone sound bright. I never get the sense that this is a dark sounding headphone at all. HD 558 is the less fatiguing headphone compared to the AD900x as the highs are not quite as loud.
 
Midrange: Forward sounding but not in your face or shouty. Can sound somewhat dry judging from vocals; don't expect liquid mids. For the price , the level of refinement is expected. Not very transparent sounding . There is some graininess and sibilance compared to some higher priced Sennheisers like the HD600. Higher end headphones sound more rich and resolving; it is hard to mistake the mids of the HD 558 as high end but again, considering the price I think most will be happy with the performance. 
 
Bass: Midbass is good to add to the engagement of the sound signature however don't expect to hear anything below 50 Hz very clearly and evidently. The bass texture and decay in the lower end is hard to hear but it can be hard for most open headphones to be great in this area. Don't expect these to make your head rumble. 
 
Details: Not the headphone that will make small details pop; it's there but I will have to listen to it a little closer compared to a AD900X which reveals tiny nuisances more effortlessly. When the track gets quite busy there is some smearing which is expected for a headphone of this price but really it is not bad at all. I think those who are looking for their first decent cans will be satisfied.
 
Soundstage: Not super wide or narrow, could be considered just right depending on where you're coming from. It does not sound artificial like some 3D effect and there is decent depth as well but not very deep. No obvious flaws or gaps. The AD900x is an example of a headphone with a wide soundstage however I feel the HD558 has a more balanced soundstage meaning that the soundstage is more evenly spaced out. The AD900x can make things sound as if the sound is only coming from the extreme end of the soundstage with some voids between the center of my head to the edge of the soundstage. Despite this, the AD900x can sound incredible with the right music sounding completely encompassing where the HD558 will fall behind. It is sort of like a movie theatre experience vs a home theatre surround sound experience.
 
I do not like the build quality very much. There are small cracks developing which is a very common issue on the side of the headphones where the Sennheiser logo is near the headband. It is disappointing this has not be resolved since the HD 555 headphones.

-Sound: Compared to my Bose QC35, and V-Moda LP2, these definitely have more depth, which isn't surprising considering they're open back. I've also found the sound to be quite nice. I'd go so far as to say they're much better than my previous favorite, the Beyerdynamic DT880 since they're much warmer, and because of that, less fatiguing.
 
-Comfort: I often give comfort priority over sound because I can get used to how headphones sound, given they're not complete garbage, and more than not, a unique sound signature adds to the music I listen to, depending on the case of course. These headphones are incredibly comfortable in both sound signature and fit. I have a normal sized head and, while they do clamp down a bit tightly, something that isn't very necessary considering their light weight, the earpads and construction of the earcups make it easy to wear them for hours on end.
 
-Open back: Spacial awareness while gaming is on point.
 
 
-build quality: for the most part, they're plastic, but well constructed. Not as creaky as a lot of headphones, but they're not the most luxurious headphones either. Overall, they're built well enough and seem durable enough to stand up to years of use.
 
-portability: Lastly, These headphones don't fold. In my case, I use these with my laptop and often need to take them places. Because of the lack of folding mechanism and/or case, they're not the easiest things to cram into a bag. Folding flat would be a welcome feature.
 
-other thoughts: the cable is very long and not coiled which is either good or bad and depends on your use case. One thing I find annoying is that my pair came with a cable that terminated in a 1/4" plug. Since I'm using this with a laptop, a 3.5mm plug would've been better. They do include a 1/4" to 3.5mm adapter, but it'd unbelievably bulky. Luckily I had a short 3.5mm male to female extension to take some strain off the adapter. Just something to think about before buying.
 
The cable is indeed removable and locks into place so there's no worry about it coming unplugged and if it were to get damaged, you don't need to buy another set of headphones.

First review but here goes
 
The Sennheiser HD 558 comes with a 3m detachable cable, a 6.5mm to 3.5mm converter and the headphones themselves.
 
Comfort and Build: Although the headphones themselves are made entirely of plastic it doesn’t feel like the cheap plastic. In fact the build seems solid enough to take light abuse but I really wouldn’t recommend anyone stress test these to any high extent. They do however feel like a well-constructed pair of headphones. In the comfort department it feels light on the head with heavy padding on the headband and thick padding on the ear cups. Both quite soft but the cloth material is a dust magnet. Even within a day of use you can sort of already see the dust being picked up by the pads. I guess it might just be my room that’s extremely dusty but just thought I’d give a heads up. Also right out of the box the clamping force is quite high although they aren’t horrendously tight (they are in fact extremely comfortable) they don’t feel like the clamping feeling around your ears are going to disappear anytime soon. Because of this my ears do get quite warm over a period of time. However that being said it does mean that when adjusted correctly there is almost no feeling on the top of the head. The cable isn’t all that special, it’s pretty thick but isn’t overly stiff terminating at a thick and chunky jack. Strain relief on both ends of the cable are more than adequate.
 
Sound
 
Bass: I wouldn’t consider myself a basshead but having a bass presence and that low rumble or pounding always helps in finding the beat of a piece. In this case you can hear the bass of a song with some bass presence but the thump really isn’t all that impressive. It’s there but it isn’t going to knock you out if that’s what you’re into. There is some rumbling when there isn’t much else in the track otherwise it just gets trampled over but mids and highs and you really have to concentrate to notice the full effects and rumbling of the bass. There just seems to be a slight lack of overall tightness in the bass, in some passages it just feels a little muddy with some bleeding into the lower mids when there is just a stampede of sound with . All in all I find the bass somewhat sufficient for me, but I would prefer to have slightly more tightness in this area for cleaner sound.
 
Mids: Ahhhh the mids, so smooth and relaxed. They never feel harsh or obtrusive, taking a more relaxed tone that is sweet and lilting. Lower strings and guitar are clear and feel extremely laid back with a light airy sound. Cellos feel just as how I feel a cello should sound for more calming pieces with viscosity and a slight warmth to them that just give you the feels inside. Male vocals are a tin bit veiled and lacking in weight and power, it seems as if they are TOO polite. This is absolutely fine for slower and more relaxing songs but when they need it for that powerful tenor sound I find a generally lacking. Female vocals are so wonderful to listen with that silky smooth flow of voices. Again however the voices are almost too polite for some songs. It’s just too rounded and relaxed it lacks the bite or attack in their voices. This is not dissimilar to the headphone in general, there just doesn’t feel like there is any bite to the sound whether it be strings or voices. This is perfect for lyrically emphasized songs and jazz that require a warm velvet sound that just allows you to relax and have a good lie down.
 
Highs: The smoothness of the mids carry over into the high range allowing for longer listening periods that have a ton of high frequency sounds. There is plenty of treble sparkle without a lack of thickness. I wouldn’t say that the highs are thick like the mids but rather there is a good balance between the two. Neither is really fighting to overcome each other and I find a good balance of the two ranges. That being said the upper registers of violins and voice are again smoothed over. There is also a sense of clarity and breathiness which make the highs all the more enjoyable. The airiness and smoothness reduces the harsh sibilance allowing in longer listening periods. It isn’t totally smoothed however and you’ll be glad to know that there remains a slight edge to the sharpness of the highs. Giving back the bite to strings which sometimes is just so crucial to make the sound much more intense than if it was totally smoothed over.
 
Clarity/Soundstage: The soundstage feels large but you will never feel that you are sitting in a concert hall. It feels more like you are sitting in a largish room. It’s certainly big enough but I don’t feel that I’m really suitable commenting too much as I’ve been pretty much using IEMs only so these are a vast improvement. Due to the larger soundstage, open feeling and breathing room between the instruments and vocals it takes a large step up in the clarity and also transparency. I can hear the subtle snapping of fingers or the light thud of a piano pedal in the recording in comparison to my IEMs which masked these tiny details.
 
Overview
For the price I paid (around $160US) I find these headphones a nice deal. It’s generally pretty comfortable (although clamping is pretty damn high >.>) and delivers a warmer, pleasing sound to slow relaxing songs like jazz and vocals but because of this it just doesn’t really have the power or bite that sometimes just makes you go WOW at the performer. The light airy sound help with relieving congestion overall, but it just really isn’t suited for intricate bass pieces as it just becomes slightly muddy even though there isn’t that much thump or rumbling. Furthermore the bass department just doesn’t have the emphasis to satisfy some users. If bass is the sole thing you are looking for in a pair of headphones maybe try to avoid these? But in my opinion this isn’t too much of a problem to me, what is the problem however is how Sennheiser decided it would be an absolutely marvelous idea to terminate the cable in a 6.5mm plug. This makes the plug freakishly long and it is a good 9cm in length when you add the converter t-.-t (like why?!). Luckily you can buy replaceable cables online so just a temporary setback although I would really have just preferred a 3.5mm jack and a converter. Another thing you should consider when buy these is the level of isolation or sound leakage. Due to the open design it doesn’t block out a noisy environment particularly well and if you raise the volume too loud be prepared to share your music with the outside world.

Comfort and build
These headphones are extremely comfortable, I have worn them for upwards of 8 hours, with out my ears hurting. The ear pads do collect a lot of "stuff" like lint and animal hair very easily. The HD558s are build very well, holding up to abuse I put them through. Even though they are made completely of plastic, it feels of top quality.
 
Sound
I love the sound signature of these headphones. The Sub-bass is satisfying enough for most music, but if you are really into Hardstyle and other bass eccentric EDM genres, these will not suffice. I found these headphones the most enjoyable whilst listen to classical style music, such as works from Hans Zimmer's, and soft house music. The only thing that would make the 558s better would be a larger, more gratifying, extension into the bass.

In my endless search for headphones that fit, and fit, are comfy, and satisfy my sound tastes; my dumbo ears have led me to very few outlets to choose from.
I chose to try the Sennheiser 558, as it gets rave reviews, and such.
Before these, I had good, but not great experiences with Sennheiser products, and these changed that for the better.
 
My first, and most important note is that these are my new favorites of any headphone in terms of sound.
1. These have enough bass, and play that they don't sound boring.
2. There is not too much bass, meaning not too much bleed into other ranges
3. The soundstage is great for the price
4. I get pulled into the music without too much detail loss.
 
These, for me, hit a special sweet spot. The SHP9500, and most of my headphones, are objectively better and cleaner, but I didn't care (and still don't). I can't put a price on the feeling these give me.
 
I can see why someone would find these not-so-good. They can be relatively veiled and uncontrolled, even laid-back.
 
I will post the bullet list I made while evaluating these in the order I noted them, and then attempt to elaborate.
 
Sennheieser hd558
 
1. love the sound.
 
When I first put these on, I immediately loved their sound. There is not much else to say. I got lost in the music.
 
2. part sticking out touches ear inside cup
 
Though the research suggested otherwise, I find that the bit sticking up on the inside of the earcup inevitably touches my epic ears. This is likely not a problem for most.
 
3. clamp is kinda tight
 
I am a bit sensitive to headphone clamp, and these clamp quite a bit, but I think most will find them acceptable. I have not noticed any loosening of the grip at this point.
 
4. proprietary cord kinda sucks
5. default cord connection should be 3.5mm, since most people with 1/4 inch jack amp would likely invest in more expensive headphones.
 
4&5 are very related, thus together. The cord is made of some awful, grippy, rubber-like plastic which clings to everything, and is also a bit springy. The cord is quite long, which doesn't bother me, as they are open. the proprietary connector on the headphone end of the cord is annoying, but can easily be modded to fit most 2.5mm, or adapted for 3.5mm cables. Lastly, the cord has a 1/4 inch adapter... (read 5.)
 
6. Keeps clarity while having enough body to pull you into music
 
This is the defining feature of the HD 558 for me. I very easily get lost in the music enough to where I forget the ear-touchy thing, and the clamping effect. 
 
7. fiio e10 is vast improvement over on-board audio sources for the 558
 
After testing the HD558 on portable, phone, decent pc onboard, and whatever else I could find; I conclude that an amp is an improvement for the HD558, even a cheap little FiiO e10. 
 
8. they look nice
 
I mean... They do to me. 
 
9. significantly better balance than g4me one, WAY cleaner (to my ears)
 
After owning these, I think either Sennheiser used HD 518 drivers, or they tried to make a "gamer" sound signature. Really, I didn't think they were that close.
I honestly think the HD 558 was superior. Less muddy, somewhat cleaner sound, better soundstage.
 
10. SHP9500 objectively better sound, etc
 
Compared to my previous daily driver (SHP9500); I think the SHP9500 was more Neutral, cleaner, and just better in purely objective terms. To me, the SHP9500 lacked bass, had a bit much treble, and were kinda dull.
 
11. My new Favorite headphone. Period.
 
I don't expect this note to be true for long.
 
12. Would love to try the hd-650, and better sources for comparison.
 
See note for 11.
 
13. after getting used to fit, the ear touching bit is a bit less noticeable. (but comes and goes)
 
14.Certain frequencies are greatly recessed. Obvious treble spike (only one spike though?)
                         ^
15. Clapping at beginning of "Bad Blood - Bastille" sounds awful.
 
*clap* sounds more like *clop*
 
17. Leather G4me zero pads fit perfectly. Zero pads add bass, decrease soundstage. Ear touches inside thing even more.
 
If you like a leathery feeling more than the stock velour pads, the pads for the G4me Zero, and similar headsets, fit perfectly on the HD558. I prefered the pads unside-down, as the inward clamp compensates well for the uneven thickness of these. The tradeoff is the leathery pads add more bass, possibly a tad muddier? and decrease the soundstage a bit.
 
18. HM5 pads could fit.
 
I would try using the plastic ring from the back of the stock pads, and putting it in the back of the HM5 pads. These have the same effect as the G4me zero pads, maybe even more-so. 
 
 
 
Conclusion: I wish these were more comfortable, and wish the cord sucked less.  I have decided to put up withe discomfort of the clamp, and the ear-touching simply because I love the sound so much, which is saying a lot for me. Gosh, they do pull me into the special, priceless place where music sounds like music, not like "a good pair of headphones accurately transcribing the sound". They sound like music to my ears.
 
The little green bar measuring thing doesn't have a measure for enjoyment, but I would give it full marks. 

These were my first headphones that got me interested in listening to music at a higher level. The sound stage is impressive, headphones are tough and well built. Extremely comfortable with nice and easy adjustments. Great intro headphone into the world of sound. They sell new for under $100 now, definitely recommend, one of the best open ear headphones in this price bracket. Also, the bass is more present in these then the HD598.

At the time of this writing, these headphones cost less than $100 on Amazon.  At that price point, they are an incredible value.  For some reason, these headphones seem to be damned with faint praise in many reviews on the web. 

What the 558 offer:
-Beautiful, natural, relatively neutral sound overall
-Forward, engaging mids (what I like best about these)
-Non-fatiguing highs
-Rich bass with good bass impact but not exagerrated bass (look elsewhere for "bass monsters")
-Wide soundstage
-One-sided, replaceable cable
-Good looks 
-Easy to drive (50 ohm impedance means you can drive these easily with iPod, phone, etc)
-Supremely comfortable on my fat head

What they don't offer (and neither did the HD600):
-Great sub-bass extension

Other points to consider
-As an open design, these do not offer noise blocking or prevent leakage (this is not a con, per se)
-They come with a 10ft (really long) straight cord terminating in a 6.35 mm stereo plug. The 3.5mm adapter is a bit unwieldy for use with phones, etc. However, Sennheiser offers a separately sold inexpensive 4.5ft replacement cable with a 3.5mm termination, perfect for such uses

If you are not using a dedicated amp and are looking to plug headphones directly into your phone/MP3 player/laptop/computer, don't need closed headphones to keep sound out/in, then IMO these are the best Sennheisers available and one of the best choices of any brand at any price point.  
 
The only limitation I find is that the bass extension is not adequate for 2% of my rap and electronic music.  Eg, ODB's "Harlem World" or MF Doom's "Hey".  Otherwise they sound fantastic with all genres (including rock, jazz, pop, and 98% of my rap/electronic).

My opinions
 
Sound
The sound produced by the HD558 is rich, a bit light, and isn't bloated with bass which is a good thing. It has a crisp treble and punchy bass, very great soundstage(expected from an open headphone) but sometimes the bass lacks. The great thing is this headphone will play any genre of music well, even from rock to classical(they play very well with classical).
 
Comfort
The HD558 is very great for listening to music for hours. The velour pads very soft and comfortable, when you put it on, your head will still feel very light, and the pads are well shaped and pads are also great at managing sweat.
 
Build
The design isn't very interesting/eye

Pros:
- Airy presentation with good soundstage (great for music and movie too)
- Balanced, entertaining sound
- One of the most comfortable headphone what i have
 
Cons:
- external amplifier (or a beefy DAP) is required for maximum enjoyment (necessary for tight bass)
- Little short of the bass quantity ( few +dB bass boost will help)
- Not the most exciting highs
- The sound is not as detailed as the hi-res headphones
- Only one long cable came with it by default

Read complete review and impressions here:
 
http://www.head-fi.org/t/540173/sennheiser-hd558-impressions-review

This was my first open headphone and I fell in love with it the moment I heard it. I would say it's a rather dark -sounding headphone with a really pretty midsection. It has a tight, well defined bass that tends to do quite well with low quality recordings (but does not extend really deep). It does exceptionally well with trip-hop artists such as Massive Attack (In my opinion).
 
This is the best budget for under 200$. It will work with a phone, and even though sennhieser recommends this, It sounds the best when plugged into a slightly better sound source like my MacBook Pro.
 
It does benefit slightly from a DAC or AMP, but not by much.
 
 
Also, people say this sounds better than the HD600 when un-amped. However, That is really not true in my opinion. BUT it's still is a great headphone nonetheless.

I Like It. I can't tell you I don't. 

 
I have only owned this for a couple months, but it did not take long to see why these are highly regarded. They quickly became my favorite all-rounder headphone for home use. I also own the Sennheiser HD 25-1 II, and Grado SR60i, I will make some comparisons to these also. Although sound quality is important, I will take a more balanced look at how practical these are to use on a daily basis.
 
Comfort/Design
 
I consider the comfort and design of a headphone to be just as important as sound quality, because this is what will ultimately determine whether I will find it practical to use on a daily basis, and whether it will last for many years to come.
 
The HD 558 is hands down the most comfortable headphone I have ever worn. The open design, the Velour headband and ear pads, the light weight construction, the perfect clasping force, and the roomy size inside for the ears all work in harmony to create what many consider to be one of the worlds most comfortable headphones, in any price range. I can wear them all day long (even with my glasses on), with no hint of discomfort, no heat or sweat issues. Grado SR60i's being on ear style do get slightly uncomfortable with glasses on over extended periods. This is a non issue with the HD 558. In terms of style, these look fantastic on your desk, or on your head. The fusion of comfort and style is truly a feat of engineering on Sennheisers part.
 
Some have concerns about the plastic construction, and what affect it will have on durability. Although I have only owned them for a couple months, I have no doubt they will last many years. The Sennheiser HD 25-1 II has legendary durability, and is completely plastic also. The look and feel of the plastic is top notch. There were reports of cracking on earlier models, but this has been addressed with newer models. Sennheiser has been great in honoring their 2 year warranty from what I have read of those affected. Heck, you have 2 years to “break” them in .
 
The only real conn in terms of design for me is the cable. The 3.5mm connector is huge, and wont fit many portables, specially ones with protective cases. And even if your lucky to have it fit, it will stick out by nearly 4inches, more than doubling the size of most portables, making them not so portable anymore. On my desktop, I use Logitech Z-2300 2.1 speakers, which have a 3.5mm input on the remote control that I used to use for my other headphones, but this connector is too big to fit, really annoying.
 
The length of the cable at 3m is over double what most people need. The fact it's replaceable is nice, however, I can't seem to find any of these cables to buy. The headphone connector is 2.5mm, but its a really narrow shaft, and most 2.5mm cables I found are too fat to fit. Plus, theres that nifty locking mechanism that only the official Sennheiser cables have. My only option seems to be to cut this one down and re-terminate it myself, or find a pro to do it for me.
 
Sound
 
The sound stage on these is similar to the Grado SR60i, that is to say, its fantastic. Yes, it will occasionally have your head turning to locate that “noise” behind you, on tracks you heard hundreds of times already. The HD 558 does this all with slightly better separation on more complicated compositions, especially in the mid range. In comparison to the SR60i, the highs are more subdued, which I consider an improvement. SR60i's are great, but the highs are a little overdone in my opinion.
 
The area where the HD 558 really takes the cake is the mids. The mids are in your face, right where you want them. They are far superior to any headphone I have in this regard. The only real conn in terms of sound, for some, will be the bass response. It is a noticeable step up from the SR60i. It keeps up well, you hear it all, but not with that satisfying punch or rumble that you would get with a closed or more expensive ($400+) open headphone.
 
The nice thing about these is your average source or portable will be able to to run them with no problem. It seems when you break the $250 price range your going to need to double your budget to get a decent source to enjoy their full potential. Not the case with the HD 558. As with most higher end headphones, these can shine even more when connected to high end amplification, but it is by no means required.
 
Verdict
 
If your looking for a great all-rounder for the home under $200, these are hard to beat. At home people tend to leave headphones on for extended periods, and you will have a hard time finding something more comfortable or better sounding in this price range. The only way I can't recommend these, is if your a complete bass head, in which case, your alternatives in this price range will be destroyed in every other area besides bass, and will leave you in a puddle of sweat within the hour. And if your looking for something portable, you should not be looking for an open headphone, specially a full size one. My HD 25-1 II is my portable headphone of choice, and the HD 558 has become my home all-rounder of choice. Between these two, I have a quality headphone for any application, at home, or on the go. Viva la Sennheiser!

Overall, I like these headphones a lot, and they provide great bang for the buck compared to other headphones I listened to in this price range. 
 
 
See here for complete review:
http://www.head-fi.org/t/618598/sennheiser-hd558-hd430-comparison