Friday, April 18, 2014

Review: Sennheiser HD-558 (modded)


Why the Hell would I need another headphone - again? I´ve asked myself this question often enough. But I don´t have an answer. I just like to collect cans. Just as I like to change playback/recording units I love to change headphones, all depending on my current mood. Pure, decadent luxury considering other people can´t afford even one headphone. Well, I received a not-so-small amount of money as a Christmas present and decided to spend a part of it on a new pair of cans. And as the Sennheiser HD-558 had been on my Amazon Wishlist for more than three years, I finally decided that the time was right. Do I like it? Is it able to replace my dearly loved, 9-year old Sennheiser HD-600? Why don´t I just use my Sennheiser HD-448? Or my Superlux HD-668B? And what about the two headphones I reviewed before, the Sennheiser Momentum and the Skullcandy Aviator? Read on and you shall be rewarded with answers, dear constant Reader.

Design & features

Sennheiser HD-558 (with 'NOS4A' by Joe Hill abused as a headphone stand)

The Superlux HD-668B cannot be used anymore since it broke apart (only because I cleaned it!). I won´t replace it with a new unit because... well, I have grown to hate its sound. The Sennheiser Momentum & Skullcandy Aviator did many things well but suffered at others, the worst being comfort-related. In the end I decided in favor of the Sennheiser HD-558, the headphone I wanted to have in the first place. It cost me 129,- Euros, it is a plain and boring looking headphone, manufactured entirely out of plastic in China. Huh? No, I don´t have a problem that it´s been built there, it´s just that Sennheiser doesn´t like to talk about it which feels pretty double-tongued. As if they are ashamed of it. When I think of my beloved FiiO units, it's stupid and not particularly fair to the people who constantly excel at producing highly functional products for the whole world. But enough of that. This headphone is right in the middle of the HD-5x8 line. All of them are engineered to attract cost-conscious people; the HD-518 is the cheapest, costing half of what the top model, the HD-598, costs (roughly 220,- Euros). Their predecessors (HD-5x5) looked almost the same, had the same features and were - as far as I can tell - fairly successful, causing Sennheiser not to change too much. Never change a winning team, eh?

A (too?) proud German company: Sennheiser

The top model HD-598 is finished in a cream-like colour with attached faux-wood veneers, a headband with a fake leather pad and metal grilles covering the outside of the earcups. Sennheiser was obviously trying to improve the inherently bourgeois design of the predecessors; yet all they achieved was making it look tacky. The grilles of the otherwise plain HD-518 arent exactly an improvement either, they look like windows shutters. The incredibly boring and plain looking HD-558 is the one that´s honest, it´s the least flashy of all three models. When it comes to features, it´s equipped with what Sennheiser calls Eargonomic Acoustic Refinement (E.A.R.), which is supposed to 'channel audio signals directly into your ears', enabling all three HD-5x8 cans to have 'outstanding bass and vocal projection'.
Ugh, simple marketing blabla: E.A.R. is nothing more than an angled driver, many headphones are equipped with a technology where the drivers are placed slightly below and in front of your ears. Our ears' stage impression usually reacts favourably to this placement because it mimics how we listen to loudspeakers: those aren´t standing on the left and right of our ears, no, they´re standing in front of us, helping us creating a holographic image of the virtual stage. Is it a good idea to implement something like this in a headphone? Well, so far my experience tells me that it rarely works as intended... with horror I recall my second 'big' headphone, the Sony MDR-CD 570. Because most of the time it just creates colourizations - and not the desired effect of a holographic stage. But we'll see about that later.

Sennheiser HD-558, earcup: comfy velours cushions & 'surround reflector'

The diaphragms inside the drivers are a Duofol design, this principle of constructing membranes was carried over from the HD-6x0 models. They reduce distortions and improve transparency, that's what Sennheiser says. Seems to be true when I think of my HD-600; it´s the least distorting and most airy headphone I´ve ever heard. When it comes to impedance, this headphone is rated at 50 Ohms. The maximum sound pressure level (SPL) is at a very loud 112 dB, it should therefore be perfectly suited for portable units. But no, Sennheiser markets it towards music lovers, listening at home using their big HiFi system. Strange. This will become important again, so more about that later.

Accessories & built quality

Sennheiser HD-558, 3-meter cable

The box the HD-558 comes in, contains the headphone and the cable. That´s it. The 3 meter cable pictured directly above (recall for a moment that it´s targeted at at-home-listeners) comes with a proprietary 2.5 mm plug on the headphones' side. The Sennheiser site lists an additional 1.2 meter cable with 2.5 / 3.5 mm plugs suitable for portable units. However, this cable appears to be a myth as I was unable to find even one place where it was sold.

Sennheiser HD-558, proprietary 2.5 mm connector - what a dimwitted idea

In the end I had to resort to a replacement cable built by Oyaide and distributed by FiiO, the RC-HD1. This took a further 40,- Euros out of my pocket. Frankly, I find Sennheisers' brazenness of not including a shorter cable themselves, insulting. A carrying bag... are you kidding me? Not included, not offered. My cheaper HD-448 came with one, the Skullcandy Aviator had a particularly luxurious bag, the Sennheiser Momentum could be safely tucked away inside a firm, brown bag. Hell, even the super-cheap Superlux HD-668B came with a soft cloth bag. With the exception of the Momentum, all of them cost less than the HD-558 and Sennheiser cannot manage to include something as basic as this? Oh please!

Quite expensive but well built 1.2 meter replacement cable: FiiO RC-HD1

But how is it built? Despite being fashioned completely out of plastic it has been manufactured very well. Everything fits tightly, fins are nowwhere to be found, it doesn´t creak when moved or when you change the position of the earcups. The cushions are firm and they are replaceable... now, that I mentioned it: the possibility of replacing any broken part is one of the reasons why I love Sennheiser products so much. By doing so, you can extend the lifetime of their headphones. My boyfriend owns an ancient Sennheiser HD-250 linear; it´s now 26 years old. With other manufacturers you´d be hard pressed to find even one replacement part, with Sennheiser it is no problem. My boyfriend has been using the HD-250 Linear for many years for DJing, it was beaten, tortured and abused. The faux-leather cushions and the mesh covering the drivers had disintegrated completely, the cable looked like shit too... well, it was inconvenient anyway since it was equipped with a 5-pole DIN-plug! Getting new earpads (including the mesh) and a cable was as easy as ordering a new headphone with the result that this ancient thing now looks like new.
Upon deciding whether I should get the HD-558 or not, I also considered the famous Philips Fidelio X1 (gorgeous sounding headphones). At first glance, it appears to be perfectly manufactured and built to last. But any impression of reliability is destroyed once you know that its cushions and everything inside it is glued together. Even the cushions are glued to their frame, they aren´t replaceable. Perfect example of planned obsolescence if you ask me and crucial for my decision not to buy it. EDIT 17.03.2015: The successor Fidelio X2 fixes that problem. Well done, Philips!

Comfort & quirks

Velour cushions & headband: comfy and replaceable

When referring to new Sennheiser cans, people usually talk about the 'clamp of death'. It´s true: the clamping force of the HD-558 is quite strong, your head is tightly sandwiched between the two earcups. Even after wearing it almost every day for more than two months, this force hasn´t diminished. The earpad and the headband cushions are firm, but not uncomfortably so. Their one redeeming aspect is their size; while the cups of the HD-600 are even bigger, the earcups of the HD-558 are certainly big enough to accomodate almost any ear.
There´s just one thing inside perhaps posing a problem: a so-called 'surround reflector'. You see, the fabric covering the drivers is applied to a thin plastic foundation which itself protects the membrane underneath it and also forms the reflector. The latter sticks out and, for me, has been a nuisance. It causes me to re-adjust the position constantly because it tends to touch my upper earlobes. This doesn´t hurt at first but after a few hours (yes, I wear headphones that long) it starts to hurt, even when it´s only slightly brushing my earlobes. Wouldn´t be any problem at all - if the surround reflector would be softer. But the hard plastic underneath the mesh averts this. So before you buy it yourself, try it on and see if your ears fit.

The foam mod & Burn-in

Did you know that you can modify the HD-558 to almost sound like the top model of the line, the HD-598? It´s easily said and done, just look above at the video. But please, be more careful than the creator of the video, the cables soldered to the drivers are very, very fragile. They break if you blow on them. According to what people say online, by removing the piece of foam you´ll get more punch and air. I cannot attest if this is true or not, I never listened to my HD-558 before it was modded. Whatever it changes, this tweak won´t completely transform your HD-558 into the HD-598. To achieve that, you´d have to grab pliers to cut holes into the plastic structure covered by the outer felt-mesh grills. The HD-598 sports very fine metal grills which aren´t dressed up with some fabric, apparently they help to achieve a more airy sound. This might be true; before I got my HD-600 I owned its predecessor, the HD-580, which is (apart from a different colour scheme) exactly the same headphone. The only difference are the driver grills: on the HD-580 they are plastic, on the HD-600 they are metal, causing the latter to sound different. But I don´t want to remove anything that can´t be re-attached again, I´ve therefore skipped this part. Below you can see measurements by Headroom where I´ve compared the frequency response of the HD-558 against the one from the HD-598. They are extremely similar, the HD-558 emphasizes frequencies around 3,000 Hz while the HD-598 slightly accents everything above 10 kHz. The latter presumably is responsible for the HD-598's stronger amount of 'air' while the un-modded HD-558 will sound a bit more aggressive. The foam mod will bring the HD-558 much closer to the response of the HD-598, in the end you have to decide yourself of course if you actually want the sound of the top model.

Frequency response differences Sennheiser HD-558 & the top model HD-598

Whatever you decide, you simply have to burn in the HD-558 (this goes for the HD-518 & 598 too). I listened to it once I had removed the foam and in spite of it already sounding very well, burning in really brought out its strengths. I admit that I´ve never experienced ANY device reacting so strongly and positively to a burn in. My Sennheiser HD-448 remained essentially unchanged in terms of sound, the Superlux warmed up considerably but these cans turned from undifferentiated into 'differentiates-like-hell'. Spatiality improved a lot, some unpleasant high frequency sibilance was removed too. So please, burn it in. For at least 48 hours.

Tech section

Impedance response HD-598 vs. HD-558 vs. HD-448/449

I know you probably hate to read measurements of any kind. They are boring, you cannot understand them or maybe you´re simply too lazy to even want to understand them, right? Yes, in my opinion, people who ignore measurements willfully do not deserve to experience sonic bliss. So stay with me and let me lecture you, for a few minutes only, I beg you. In this case it´s important because they tell you if the HD-558 needs to be amped or not. Because the answer is YES and NO.
NO: It´s loud enough for many portable devices. At this moment I´m listening to music played back by a recently acquired Sony NW-HD5 (review will follow) and with the HD-558 it gets loud enough to shatter my ears. The same is valid for many of my portable MD recorders/players. Not to mention the FiiO E07K and the FiiO X3 (review will follow), they can kill the HD-558 with ease. Sensitivity isn´t any problem, the impedance is. YES: The HD-558 is rated having an impedance of 50 Ohms. Look above at the measured impedance response and you can clearly see that it reaches a resistance of almost 300 Ohms at 95 Hz. Meaning: a headphone output with an output resistance of more than 6 Ohm will produce severe frequency distortions.

Well suited for portable units - but not for stationary units: HD-558

Example: to monitor an MD I was recording with a Sony MDS-JE 530 (review to follow), I plugged the HD-558 into the MD-recorders' headphone socket. The resulting sound was so bass-heavy that it obscured everything else. Mids and treble were drowning in bass, it was unbearable. Beats by Dr. Dre territory? Think bigger, more blown-up and hollow. What my problem is, you ask? I´ll tell you: many big amps, CD players, network players or TVs are equipped with headphone outputs featuring a fairly high output impedance. With all of them the HD-558 will produce this bass-heavy, highly coloured and droning sound. But if all of them are playback devices for usage at home, then why was the HD-558 engineered in a way that will produce a bad sound with exactly these devices? Remember: Sennheiser targets these cans at at-home-listeners... why the fuck did they construct a headphone that will play with superior quality on half of all portable devices instead?
Thankfully I´m accustomed to amps with a low output impedance. In case I want to use it with one of my vintage portable CD players, I simply connect either the FiiO E6 or the E07K. Or I make use of the FiiO X3. Due to its fairly high sensitivity you might want to listen with it once you step outside... you'd look ridiculous though. And don´t forget that it is a very open headphone, leaking a lot of sound to the outside world. What you´re hearing, other people will hear too. So what is it for? Portable use? Electrically, yes. Isolation? Forget it. At home? Yes - but only with sources having an output impedance of less than 6 Ohms.

And now: the sound

Sennheiser HD-558: felt mesh grills

Does it sound well? Of course it does, otherwise I wouldn´t have kept it. Once it´s modded, burned in and fed by low impedance sources, you´ll be rewarded with a stage like you´ve never heard before. Only one word fits: spectactular! For decades I´ve been dreaming to hear a soundstage like this one and until the HD-558 arrived, this desire had never been fulfilled. My beloved HD-600, already featuring a realistically wide and deep stage, feels shallow in comparison. Yup, the HD-558 easily bests the HD-600 in spatiality. It´s like being able to 'see' around instruments, effects, soloists, anything. The sound is fantastically layered, not only from left to right but from the front to the rear. Every instrument, group of players, synths and effects, even reverb, is defined precisely. It doesn´t sound artificial, it feels completely organic. Very well done, Sennheiser!
The impression of virtual stage depends on the recording you´re listening too, of course. The device used for playback and amping plays an equally important role, too. For example, these cans revealed my FiiO X3 to sound a bit distant, compact and slightly constricted (I knew that before, the HD-558 only made it all the more apparent). The more recent FiiO X5 (loaned to me by FiiO, review to follow) was worse, sounding flat, confused and blurry. 'Stage kings' like the Sony MZ-R 37 or the MZ-R 55 are unmasked to sound either artificial or congested while the MZ-R 50 improved. Recordings produced using several groups of microphones profit as well, recordings with less mics will extend their dimensions. Binaural recordings... superb. It appears that the Sennheiser marketing experts haven´t promised too much when advertising the HD-558 as featuring an improved spatiality.

The fantastic stage of the HD-558 is... hard to match

Frequency response is a bit more problematic. There seems to be almost no sub-bass (below 50 or 60 Hz). Yep, deep bass is lacking badly, causing a "loose" sound signature. I´d guess 6-8 dB amplification below 60 Hz might do the trick. Frequencies above however are fully present and accounted for... which is also the reason why an impedance mismatch like the one I described above will produce a hollow and bloated sound. But when properly amped, bass is punchy when needed, dynamic and reasonably tight. Everything above low frequencies sounds balanced with a tendency towards warmth and charm. Voices have a correct chest size and won´t ever sound sibilant. Overall, I´d call the frequency response fairly leveled out from 100 to 10,000 Hz without too much colorization. My HD-448 sounds muffled against it, the Superlux... well, when it was still able to sound... no, I don´t want to compare it, it´d be insulting to the HD-558. Still, just as it would profit from more deep bass, a stronger amount of air / crispness would be benefitial as well. Sometimes it sounds rather dry; this helps differentiation and precision of course, the HD-558 will always be able to tell things apart with ease, better than the HD-600 even. But air is missing and a too dry sound appears abrasive to some people. Though 'abrasive' is the last word I´d use to describe the HD-558. But there´s no denying that the HD-600 is superior when it comes to air.

Could have more 'air': HD-558

Another area the HD-600 easily surpasses the HD-558 is the amount of details. Due to its slight warmth and missing air, the HD-558 drops tiny details. Revealing errors isn´t its forte, no, it´s a headphone concentrating on presenting music pleasantly. But don´t make the error to think that it sounds boring or that its timing sucks! Far from it, this is one of the most vibrant and snappy headphones I´ve ever heard. One minute, it´s explosive and calm the next, it sounds much more engaging than my HD-448. It can be lovely and aggressive, all depending on the recording. Will it ever sound congested, plastic-y, confused, coloured, veiled or boring? No.

Now a warning: all of this depends on how it sits on your head. The position is extremely important for the sound and no, I´m not exaggerating. Moved too far back on your head it´ll become more airy, stage will be wider but shallow, moved too far to the front it´ll sound coloured, veiled and hollow with a strange stage. This is the moment where the angled driver design rears its ugly head. All headphones more or less depend on being correctly positioned to be at their best, this is equally true for the HD-600 and the HD-448. In case of the HD-558 however the effect of a wrong sitting position is much more detrimental than I expected, to find the golden mean thus is vital for a perfect sound.


Put it on your head, grab a good book and dream away... crap, that was corny :)

The Sennheiser HD-558 (and when it comes to sound, the HD-598 too) is a wonderful headphone: well built, important parts are replaceable. The latter will extend lifetime of this headphone far beyond of what people are nowadays used to. It isn´t a perfectly neutral headphone, it´s a bit warmer and more charming than necessary. More air would surely improve its sound; more deep bass would too. The impedance response sucks - big time. It´ll only sound perfect with many portable devices, yet Sennheiser exclusively addresses home stereo listeners. Unwise of them to create a headphone that cannot decide which personality it´s supposed to embrace. Additionally, the bourgeois design could deter people from taking it seriously. If you can accept all that, you´ll be rewarded with a stage performance besting every other headphone I´ve ever heard (and there were many). A precisely defined rendering of objects on the virtual stage combined with a fantastic sense of space surrounding these objects... as if you would take an auditorally magnifying glass to zoom in on something without ever loosing the bigger picture. It doesn´t sound boring but vibrant and apart from the warm tilt it´s neutral enough to objectively judge sound quality should you so desire. Add to that the comfort and you'll end up with a headphone that´s wonderfully suited for hours and hours of aurally pleasure. Just use it with amps having a low output impedance, adjust the position on your head until it sounds best and you´ll be having fun for years to come. Recommended.

  • incredible stage performance; surpasses every other headphone I know
  • vibrant, yet pleasant sound
  • neutral from 100 to 10,000 Hz...
  • ... with warm & charming character
  • good differentiation
  • good precision
  • no distortions at all
  • good timing
  • loud enough with portable units
  • very good built quality and haptic
  • comfortable to wear for extended amounts of time
  • earcups big enough for almost any earform/size
  • can be modded almost to top-of-the-line model
  • most parts can be replaced

  • sound depends a lot on correct sitting position
  • no bass at all below 60 Hz
  • could be more airy above 10,000 Hz
  • highly problematic impedance response
  • 'surround reflector' inside earcups might hurt upon being touched for longer periods of time
  • comes without accessories like bag or additional, shorter cable
  • short cable comes extra & is nowhere to be found
  • conservative, boring design

Last update: 17.03.2015


  1. Does hd 558 fit in the hd 448 pouch? ?

    1. Barely. It gets squeezed a bit too much for my taste.

  2. So hat AMP do you advice? I would like to spend no more than 50€

  3. great article!

  4. Thanks... Helped me narrow down to this done over Audio Technica M50X, mainly because of the open back design and its more realistic sound. By the way, I do not own an amplifier. Can it be powered through an iPhone and Macbook Air. I'm going to use mostly these two devices. If not, which amplifier would you suggest that won't burn my packet :P

    Thanks :D

    1. Don´t be so hasty! :) The ATH-M50x is a fantastic headphone, too. I´ve owned that since last year and apart from too much bass & treble and slightly diminished lower mids, it´s a flawless headphone. Though not everyone likes the comparatively small earcups.

      The HD-558 might not get loud enough when powered through iPhone / Macbook Air. An iPhone 4s certainly didn´t have any problems driving the ATH-M50x but then the Audio Technica is easily driven and doesn´t need a seperate amp. The HD-558 might, especially because of its problematic impedance response. I guess, you have to try it to know.

    2. My Note 3 and Nexus 5 are not able to drive the HD558 to any decent level. However my Macbook Pro does a nice job so your Macbook air would do just fine. I havent tried the cans with any iphone though. Im using Fiio E07k as my amp. There are many options available from fiio at very good prices.

    3. Thank you for your answer! It´s always nice when someone else chimes in to help. Much appreciated :)

  5. Thanks a ton guys....
    Your comments really helped me a lot. Since I was looking for a better sound stage, I bought HD558. Don't know if the additional 60$ upgrade to HD598 was worth or not, and thus I decided to stick with HD558 instead. I tried both and couldn't feel any difference between the two except the looks (I'm no audiophile though :P)
    M50x is amazing too by the way. Much better bass like Jörn mentioned...

  6. Thanks for your very detailed review! I bought them about 4 weeks ago and burned them in for 3 weeks. I compared them to the HD 598's, doing A/B comparison and found that the low end was boomier and the high end was a bit harsher. I removed the inner foam pads and the sound was smoother with a wider soundstage....more midrange than before and more pleasing.

    The impedance/frequency graph was very helpful! I noticed that the low end was a bit sloppy and lowered the eq at the 95 Hz mark until the sloppiness was gone. I guess it would be easy to make an impedance adapter with a couple 220 ohm resistors in parallel to increase the headphones impedance to 272 to combat that 275 ohm impedance/frequency spike.

    1. Very good suggestions! Thank you :)

      Or you could just buy a completely different headphone ;)

      I´ve listened to the HD-380 Pro and I´m actively thinking about purchasing that one instead. What I miss from the HD-558 is deep bass and high treble, the HD-380 Pro is a bit better in that regards (but the impedance issues remain all the same).

  7. My brother owns the HD 380 Pro's and I borrowed them for a little bit before I bought the HD 558's.
    I found the sound to be sterile and dry sounding. After owning these HD 558's, I cannot go back to closed headphones :)

    BTW, I made an impedance adapter/volume attenuator, running it through my sound card and listening to dynamic music on Foobar2000 - I can't stand compressed new music :/
    It tighten the low end and added clarity; plus, more refined volume control. I'm very much pleased with the result :)


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