Sennheiser HD 558

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.

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.

-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.

About Me:
I'm just your average guy making his way through college with a passing interest in audio fidelity. I'm NOT an audiophile, but I've got a little experience ranging from lower-end products to flagship designs. I don’t make professional reviews and by my own account, I’m not much good at describing what I hear either. But I’ll do my best and we'll just have to see how that goes.
 
Introduction:
The Sennheiser HD558 is a full-size open dynamic driver headphone. It has been on the market for several years now, proving itself to be a very capable set of headphones for a reasonable price. Sennheiser has been in the headphone game for a very long time and while it’s very well known for mid-fi offerings like the HD600/650 and flagship HD800, the HD5x8 line is the most recent iteration of their affordable open headphone design.

 
Disclaimer:
I’m not the most eloquent or well versed in describing what I hear, so take my words with a grain of salt. Also keep in mind that everyone hears differently; it’s not bad, it’s not wrong, it’s just different.
I bought this HD558 over 3 years ago and it’s served me well.
For this review, the HD558 is connected to a Firestone Audio FUBAR IV Plus, using USB input from a Macbook Air supplying lossless and .mp3 audio files.
 
Packaging and Accessories:
The packaging for these “lower-end” Sennheiser headphones is really nothing special. Honestly, it feels quite cheap. A cardboard box with clear cutout to show off the headphone, the removable 3m cable, and a 1/4” to 3.5mm adapter are all you get from the box. No padding, no felt, no carrying case/bag; the presentation felt as cheaply Spartan as could be. It’s a stark contrast to the nice acoustic foam padded cases for the HD600 series and up.
 
Build Quality and Comfort:
Let’s start off with the build quality. For a set of headphones that costs $120 (when I bought them), they don’t really stand out in any way in terms of build. When I got them, it felt sort of cheap, but now I recognize that it’s almost par for the course. The entire headphone is constructed of plastic; the outer headband shell is plastic, the cups are plastic, and the inner adjustment band is plastic. It’s all made of this solid, but cheap feeling, scratchy lightweight plastic. The adjustment band clicks for adjustment, but no indicators of any sort how many clicks you’ve gone, though it is of a good fine scale. The cable: I’ve got some nitpicks with the cable Sennheiser includes as well as the adapter. The cable is 3 meters long and it’s pretty well relieved, terminating in a standard 1/4” jack. It’s a little rubbery and springy, but not too bad and of appropriate thickness in my book. That concludes the good/okay parts of the cable. Firstly, it’s 3 meters long and while some people like that length, I find it way too long for my desktop use; that’s just for my personal use, I recognize some people like that length but I’m just not one of them. Secondly, the cable is removable, but it’s a proprietary 2.5mm twist-lock connector. In a consumer budget-friendly headphone, what’s the problem with using a 3.5mm stereo connector? Why use a twist-lock 2.5mm stereo connector? Then there’s the adapter Sennheiser supplies with the cable for those who need to plug into a 3.5mm jack. They give you an adapter that essentially creates a 5-inch mass sticking out and hanging onto dear life by the 3.5mm connection plugged into your device (amp, phone, etc.). The reason this pissed me off was because Sennheiser itself makes a better adapter that it could’ve packaged with the HD558. The sleeved cable you see in the pictures is the aftermarket cable I bought, which includes a screw-on 1/4" adapter.
 

 
On to comfort. Sennheiser usually scores very high marks here in my book. Well, at least the higher-end models do. I’m afraid I can’t be as generous to the HD558 in this regard, though it’s not to say everything’s bad news. The headband uses a single large velour pad for where it contacts your head for even weight dispersal and the earpads use the same soft velour. The earcups are adequately large for my ears, but more importantly, they’re oval shaped! Manufacturers really need to realize that human ears are not circular. The problem with these is the clamping force; there’s a lot of it and you feel that pressure the moment you put them on. This clamping pressure is also a noted trait of the HD600/650 line, but those headphones have a metal adjustment band, which can be stretched and bent appropriately to fix the clamping pressure. No such luck with the HD558; the plastic adjustment band has stayed in the same rigid shape since day one.
 

 
Sound Quality:
Let’s be honest, this section is gonna be kind of a mess. I’m not able to describe sound very well and what I can describe is only going to make sense if your mental references of all the terms are similar to what I’ve got going on in my head. Nevertheless, let’s give it a shot anyway.
 
To my ears, the overall sound signature of the HD558 could be described as tonally warm with a slightly mid-forward sound. This sounds like a baby HD600 and at $120, that’s a very good thing. It’s overall laid-back in terms of speed, but the notes feel accurate and cohesive. This versatility helps it be great at most genres.
Sound stage is pretty average for an open headphone but the imaging ability makes for good placement of sounds.
Treble is very relaxed; I wouldn’t say it’s recessed, but it’s polite and non-intrusive resulting in a fatigue-free listening experience.
As said earlier, I feel this headphone has a slightly mid-forward signature and the quality is up to snuff as well. Instruments have the right ring and musicality and vocals are clear and have nice warmth and body.
The bass is there, but like most open headphones, is lacking in weight and impact. For my tastes, there’s enough quantity and quality is good. Bass response feels relatively tight, though it’s still at little fuzzy at times. The problem it encounters, which I feel many open headphones do as well, is the lower the frequency, the less accurate and resolving it becomes. It stays quite cohesive in the mid-bass area, but gets looser the lower you go and can’t extend into those lower frequencies as well as high-end open headphones. For example, its bigger brother the HD600 does better. Because of this and its bass-light nature (compared to closed headphones), the HD558 doesn’t deal weighted blows and some music, EDM especially, loses a little bit of energy due to the lack of punch.
 
Music/songs used during the review:
Rumours (feat. Mark Johns) by Gnash
Halo 3 OST by Martin O'Donnell and Michael Salvatori
Clear (feat. Mothica) by Pusher
Cowboy Bebop OST by The Seatbelts
Sunday Morning by Maroon 5
Neon Cathedral (feat. Allen Stone) by Macklemore & Ryan Lewis
Ants by edIT
25 to Life by Eminem
Kick, Push by Lupe Fiasco
Freaks and Geeks by Childish Gambino
Flynn Lives by Daft Punk
Stop and Stare by OneRepublic
Shoot to Thrill by AC/DC
Lost Stars by Adam Levine
Beyond Monday by The Glitch Mob
Darling VIP (feat. Missio) by Said the Sky
 
Conclusion:
The HD558 is an older headphone now at this point, but for today’s asking price ($100 on Amazon at the time of this review), it’s still a very good headphone. The plastics might feel a little cheap, but they’re sturdy and the pads that contact your head are all very comfortably padded with velour. Overall, I enjoyed the slightly thicker mid body complementing a relatively neutral (with a warm tilt) sound signature. Several years ago, this was the first full-sized headphone that I bought with my own money.  I had hoped that it would be an incredibly good headphone and after several years and even a few upgrades along the way, I’ve come to the conclusion that the HD558 has lived up exactly to my expectations. It is indeed a very good headphone.

For the money they are extremely comfortable, sound great plugged into my Onkyo TX-8255 receiver playing either music or watching videos from my pc through the Onkyo.  I know you can spend many times more (a little more for ex on the HD 598s) and there are some great phones but for my classical and jazz lossless music they are amazing.  I prefer open headphones also so these well as they say "fit the bill".  I'm not saying others may prefer for ex Grados, Audio Technica and others and headphones & speakers are very much individual taste.  I owned some very accurate Grados and for me these are much more comfortable. I will rarely if ever be connecting them to my iPhone (for which I have a headphone amp) so again they fit my receiver phone jack perfectly.

     Oh Sennheiser, I'm in love with these headphones. Honestly. Everything is perfect with these. Before I continue with this review, let me make this disclaimer. I am not a "Professional Audiophile". I am just a guy with a love for audio. Now since this is out of the way, I can get to the review.
 
Comfort:
 
  These headphones are really comfortable. Like, REALLY comfortable. This is easily the most comfortable headphones I've worn to date. I honestly can't remember the last time headphones felt like this. I've let my friends use them. One of them exclaimed "What material is this? It reminds me of fabric you'd feel in some kind of car." I can agree to this. The velour feels amazing. From the headband to the earcups, they feel oh so right in every way you could think of. The earcups move back and forth, and side to side a little bit. The headband adjusts 18 clicks, so they should be able to fit every head imaginable.
 
Design:
 
 You have a removable cable like most headphones these days. I think these headphones look amazing. They are open backed as well if you couldn't tell right away. The design is so good they reused it for the special edition of the 598's. If this doesn't show you how amazing the design of these headphones are, I don't think I can help you. Your vision may not be 20/20.
 
Sound:
 
 It is phenomenal. I don't know exactly what Eargonomic Acoustic Refinement (E.A.R.) is, but whatever it is exactly, it works. I am a huge anime nerd, so I tested these headphones out with the Mushishi soundtrack. My god. Everything was perfect. Highs, Mids, and Lows. It blew me away. Umi Sakai (Unasaka) Yori sounds god like. With it's dreamy plucks, piano, and low bass hits. Everything just melts together perfectly. I could almost tear up just listening to this song. That is how good the sound is on these. This isn't boomy bass though. It is tight and perfect. If you are a basshead, don't even think about purchasing these. These aren't made to push out booming and flabby low end. If you like tight accurate bass, you'll love it. This doesn't mean it's not there. It's just accurate. Electronic Music more your liking? Great! These handle Electronic music nicely as well. If Jazz is more your forte, this are perfect as well. The whole Fallout 4 song list shines on these. Speaking of gaming, these are also great for those! These headphones take anything thrown at them with ease.
 
I also tried the mod, but honestly I can't tell the difference at all. Might just be me, but eh. Anyways.
 
In conclusion, if you are looking for a pair of open-backed headphones under $100, these should be at the top of your list.

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. 

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).

When I bought the headphones I was amazed at the comfort level these headphones offer. I must admit this is my entry into the world of premium headphones, and I truly feel pleased with my decision. So it goes without saying I'm NOT an audiophile. 
 
I'll keep this video short and crisp.
 
These over-ear headphones offers premium comfort with near sonic perfection. I was amazed even after keeping EQ in the flattest possible setting in my amplifier these babies sounded so detailed. This meant two things, Sennheiser is truly giving you a neutral sound and if you want you can tweak the EQ to give the bass, mids or highs a little push to make it shine all the more. I plugged into my amp as well as in portable devices and as expected the full blown setup brought out the jewel in it while the portable devices sounded detailed in their own right. Being an open back headphone made my ears sweat less but also made sure everyone surrounding me got a taste of what I'm listening too. So if privacy is you're concern make no mistake it'll be intruded once you get these!  
 
A few scenarios:
Gaming - One of the best headphones for gaming simply because of the wide sound stage and correct frequency response.
Movies - Again the feeling of having speakers in your room while listening to them makes them awesome for this purpose!
Music - If you're into all genres of music it is perfect for you! However if you're into only contemporary forms of music (like electronic, trap music and the likes with extended bass lines) and crave for enhanced bass you must look elsewhere.
 
 
So apart from the great sound and supreme comfort in this price bracket what else do I have to say...pretty much nothing!

If you're a newbie like me just shut your eyes and make the purchase and you'll be fine...actually more than just fine! On the contrary if you're a veteran and want something in this range you'll know better and will be able to define how wonderful these sound!

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.

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

When looking at a headphone, you almost always forget that the more pretty, or whatever in may be that wins you over in this case, that headphone, it has a sibling.
This is the brother of a widely loved, and chosen as best for $200 bang for buck headphone, the Sennheiser HD598.
 
If we look around the headphone, there's really no difference when they sit side by side, maybe one has a bigger logo on the opening, and you also notice a huge contrast.
I'd argue that an idiot who looked at both of these would choose the 598 just because of its smooth color, and someone who didn't mind price would grab the 558, do research, and still appreciate his purchase.
The differences are fairly large in the grand scheme, but if you wanted gorgeous quality, and a fancy pair of cans you'd choose either of the two, let's be real. These two both look better than the Momentum. 
 
So...
Sennheiser HD558 vs. Sennheiser HD598
 
First up, Sennheiser HD598
So, in my original review I wasn't very considerate of these, and that's not the case fully.
The 598 is a lovely can for someone who can appreciate a wide open soundstage at $150-200, and they do it best in this range. I feel in this price range, when going for a can you wanna use often, you should often go for something more close, especially if it's your first pair of headphones.
My argument? Not everyone's ears are going to understand the point of an Open Ear/Back Headphone. But it's your money, you decide.
 
Mids:
The 598 is honorably a great listening piece, and warm like both cans in discussion. Though the emphasis is very different, the details to mids in the 598 is pretty forward, the mids are nearly close to fully bodied with detailed tones on most acoustic tracks. The mids aren't aggressive in most cases, but I heavily recommend an amp, and slight tuning. Working the mids around with the EQ without an amp can pump up the mids, and definitely begin to show highlights when you listen to the Slow Post-Rock/Trip Hop of Massive Attack, and Bowery Electric, or you can EQ them properly and pull some really gentle, crisp, and almost whisper sounding mids.
I really recommend giving them an EQ if you wanna use them for portable house listening and not have to worry about amping them. My ending statement, they're beautiful, warm, and can be tuned to come off clean and crisp.
Vocals don't come off too bright, they properly lay in the middle of everything without becoming overpowering.
 
Lows:
Let's discuss Lows with these.
Lows aren't a huge strong point for these by default. And it makes me wish we all used the same players, because I've got great tuning for these.
So these headphones aren't genre specific by any means, but! I don't recommend these if you're a Hip-Hophead who wants to blare his favorite bangers at top notch volumes, I'd promptly ask you to stop reading and look at the M50, SRH840, or MDR-7506, you're not gonna enjoy these cans as much.
So I said they aren't for Hip-Hop fans, correct! It's listenable, but I feel these headphones cater a lot to different genres.
Genres with more vocal coverage work awesomely with these! The headphone takes a lot of focus and buries it around a mellow, but warming bass, and not strong by any means, maybe a bit slim, but they are detail headphones.
Without an amp the Lows are great if you can find that tune, they'll pop a bit more without an amp, and may come off a bit more slim as I said, but it's what they do best! Jazz, Classical, Orchestral, & maybe even Blues come off with a detailed pace, heavy instrument focus, and no stress on any elements.
 
Highs:
Personally I feel the HD598 has a huge emphasis on the true acoustic measurement of a studio recorded songs tracking.
With all the elements in a song creeping up on you, you never really know what you're going t get out of a song with each full listen.
Cymbals are prominent, and very detailed, I'd arguably call them relaxed, which I think is good for beginners.
To myself, they don't have a whole ton of Splash, but you do get it in a Clean measure, definitely makes the Cymbals that come from the M50(my last headphone) swallow their tongue.
 
Conclusion:
Detailed beginner can, and relaxing, very clean, not too forward. I feel these provide something new with every listen, they are a bit of a unique character when it comes being a detailed pair of cans.
Warmth is very prominent in these at immediate listen, vocals are delicate, but very different from what AudioTechnica does with female vocals.
I hope that if you decide you want one of these, and you come to this site this really helps you get an idea.
 
If you get the HD598, here are some recommended Albums, & Test Tracks(My Taste):
[track]Angel Olsen - Windows[Jangle Pop]
[track]Wolf People - Morning Born[Woodsy Indie Rock]
[album]Tool - Lateralus[Progressive Rock]
[track]Alvvays - Adult Diversion[Indie Pop(Really Candied Fuzzy Pretty Indie Rock Based Pop)]
[album]Dan Wilson - Free Life[Pianist Rock/Singer for Semisonic]
[track]Best Coast - Our Deal[Beachy Rock/Female Vocalist(Best song I've listened to in the genre, brings out the patchy guitars notes, and truly makes the other Cymbal based instruments shine)]
[track]Miami Horror - Infinite Crayons[Synthpop Revival(One of those tracks where the beginning atmosphere shine right through, and you're greeted by warm male vocals with a soft background inhales)]
[album]Ty Segall - Melted[If you're into cruddy Lo-fi, this album is something that'll make this headphone sound "fun"]
[track]The Moldy Peaches - On Top[Anti-Folk(An Anti-Folk track with a cute soundstage. Just listen, make fun of me later)]
[album]Neutral Milk Hotel - In The Aeroplane Over The Sea[It's a Cult Followed Indie Classic not everyone will enjoy, but I thought I'd throw it in for good measure, (listen if you're an acoustic fan)]
[track]Amy Grant - I Will Remember You[Random find, great for beat tracking, in my opinion]
 
So, we've discussed the 598
 
REMEMBER!
Before we jump in, I don't feel as if a certain headphone is better than another! Not with any headphones. 
I see headphones as a thing with a personality, and each does something different, which makes us choose an older headphone over a newer one, or other way around.
 
The Sennheiser 558
The 558 does have a role that you're not going to catch on the 598, again. All headphones are different, they're basically a personality. 
For the price, you get the same sized package. 
My argument here is actually pretty different. If you want a headphone similar to the HD598 at a cheaper price, get the HD558. I also feel it's safer getting into these first!
If you came from the M50, and were to ask me for something Open Ear/Backed for $100 or a bit more, I'd recommend these in a heartbeat.
Why I'd Heavily Recommend To An M50 User
These cans are my style, the HD598 belong to my brother anyway.
Dark, Smooth, and sound Luxurious to any who prefers a thicker sound.
They're quite a bit Bass influenced in my opinion, not HUGE BASS, but bass that shines brighter than what the HD598 provides.
An M50 user could get used to these with a proper EQ, and perhaps fall in love if he/she were open to Open Ear/Back Cans.
HD598 & HD558 True Difference
They're both gonna provide a warm sound, but hand in hand, if you want a Mid focused headphone, the HD598.
The 558 carries a good portion of that detail, but lays the warm blanket over it's head with a smooth, thick, warm bass. It lacks in depth at some points, but sill fares to it's own.
Mids:
The 558 is extremely unique!
The mids will almost seem squished to you, they feel really shut into the background, which isn't bad at all for a darker sounding pair of cans, it's almost pleasing if you bought these for relaxing.
You get a bass that's fit in really well, tight at points, but doesn't choke out cymbal points. And on acoustic songs with a bit more Synthesizer in it, it's a sexual feeling almost... To the point to where these cans can be so warm, with closed eyes I felt as if vocalists were pressed against my chest and singing in my ear. 
I want to warn people about using an EQ an messing up the bass too much, the bass is nice and rich like dark chocolate where it is stock, but if you over-tune the bass signatures, you can accidentally close out vocals on tracks at times, and the headphone loses its origin.
Vocals are an important part of the discussion. While they are formed kindly into the background, they are piercing, and fierce! I almost get a Grado Labs styled vocal presentation.
Male vocals that are more light will show better, and vocals in general shine on both at nearly the same frequency.
 
http://graphs.headphone.com/graphCompare.php?graphType=0&graphID[]=2861&graphID[]=2851&scale=30
 
Don't take this to the extreme, but do you research! Sound is subjective. If it's good, you've owned/own them both, and you have different listening situations for them both, then that's your taste, there probably isn't anyone out there with your desires. 
Your EQ is subjective to your sound preference.
 
Lows:
The treble might come off as a rumbling form of treble. I found this to be a strikingly good thing!
I enjoy that feeling of a 450,000lbs rock tumbling down a cliff, and you hear every pleasuring detail. I'd argue that the bass is more pleasing, yet remember, this is a dark headphone.
Bass is an Open Ear/Back generally brings in that warmth.
So, as I described the mids, they feel pressured onto you, and if you love warm, smooth bass, this is up your alley.
The headphone excels in the lows, but I feel they do their job of comforting your ears all round. This is definitely a headphone for getting home, and just laying down, or prancing around the house with these on.
My last bit on the lows, they're literally dark, no question.
I don't recommend these to anyone who wants a nice bass, but less warm feeling, I'd shoot you to the HD598.
 
Highs:
The highs are not much like the HD598, they've got some traits, but the Cymbals in tracks pierce more, the drum set stays like it should, balanced. But detailed.
I'd argue that the HD598 has more detail in the highs, and the HD558 keeps them placed in with the lows in the mids. Sure, you're definitely going to notice the highs with the HD558, but they attack you almost again like a Grado Labs Headphone. I really can't sign off a lot on these as there a bit more different.
 
Conclusion:
These are something everyone might be able to appreciate.
They're a 24/7 Headphone for me since I can't/don't need $400-700 cans.
There's really something special about these, and the reason I say that is quite simple. They aren't much like their younger brother the HD555, those are for a different sort of person.
But when I say special, I feel these definitely do their job better than a lot of headphones in their price range. 
 
If you get the HD558, here are some recommended Albums, & Test Tracks(My Taste):
[track]Pure Bathing Culture - Pendulum[(http://purebathingculture.bandcamp.com)Synthpop/Dream Pop]
[album]Mac Demarco - Salad Days[Indie Rock, Pretty Patient(An album I feel the HD558 used to focus more on the separation, and it gets warm as well)]
[track]Dent May - Born Too Late[Indie Pop/Synthpop(A summery album, but the vocals on this song shine through as warm, and relaxed)]
[track]Tamaryn - Mild Confusion[Shoegaze(You'll understand! Shoegaze is amazing for these cans!)]
[album]On An On - Give In[Shoegaze/Synthpop]
[track]Factory Floor - Fall Back[Electronic Post-Punk(Bass Heavy, crazy track)]
 
 
Final Thoughts
I've not had the cracking experience, and from what I'm aware of, it's only common in people who aren't careful, I'm not sure though.
 
I personally use these both, I prefer one over the other, then again, the one I'm craziest over is mine!
I hope this was somewhat helpful to you.
 
 
 
My reviews are more of tales, but with a nice quantity of headphone experience, but I like including the other things that really tell you more about my experience. It helps you picture them in your life if they were on your list, and gives you things to consider.

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!

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.

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.

So, these were purchased on September 17^th of this year from best buy online for $179.99, and I was overcome with joy the very second I submitted the order. I actually have never owned a pair of these before, so, I knew this was going to be a new experience for me.
 
I waited day in and day out patiently hoping that they would arrive soon, and guess what? My patience paid off. About 2 days after I had placed the order, they had arrived at my doorstep. Once I opened the box, I was actually surprised at how simple the packaging was. Nothing fancy. You get the headphones and the detachable cable. That is it, and I was ok with that. When I plugged them into my FiiO E17, I started to smile inside. I was very surprised at how balanced these were. As I started to listen to these more and more, the openness of the sound and the clarity in the midrange and treble became more and more noticeable.
 
Lows/Bass: Well refined, but not overdone or bloated in any way. I don’t listen to dubstep or bass oriented music, so bass was not a priority for me. It blends into the midrange very well, and it never gets to that point where I want to take these off or where my ears are fatigued.
 
Midrange/Vocals: Clear, easily heard, and never boring to listen to. With enough detail to satisfy even the pickiest people, i think these have the potential to be one of the best vocal performing headphones that i have heard.
 
Highs/Treble: The treble is easily heard, but it takes a back seat to the midrange, but just a bit. I think that was done on purpose by Sennheiser so that people will be able to listen to these for a longer period of time.
 
Soundstage: This portion is really great! The HD518, 558, 598, and other open back headphones from Sennheiser really succeed in this region. It is very 3D like. I am able to hear individual instruments clearly. Part of the music was in the back of the room, and the other was in the front. Like that basically. Everything was very enjoyable.
    
Conclusion: To wrap up this review, I highly recommend these at the $179-$200 price point. I got these for $179.99, like I said before, and I think, at that price, it is a steal. Overall, these headphones are really great! I cannot stress that enough.

I Like It. I can't tell you I don't. 

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.

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