I like them.

I bought them as an upgrade for HD-215. I needed better isolating headphones because of the noisy environment. I was trying several models (Technics, Pioneer, AIAIAI,...) and I loved these the most. Sound quality is #1 reason for me. They might be not the best looker but I use them as all-round headphones while commuting, DJ-ing, at studio or at home. The only downside I found so far is they are little bit uncomfortable when wearing for a longer period of time, especially together with glasses.

This is my reference for what a portable closed headphone should be.
It's neutral and sounds good on all genres.
It's not a giant killer like the DT531, but keep in mind it is closed and portable and has the most durable build quality of anything I've seen.
Also, it has the cheapest, most cost effective upgrade available for it, the upgrade to an HD650 cable.

In my opinion it is the second best deal to be had in headphones for a beginner to this hobby, second only to the Beyerdynamic DT531, if you can find it.
The Beyerdynamic DT531 has better high range sparkle and soundstage, but less midrange realism, depending on the genre you're listening to.
Anyways, neither are a perfect headphone, and calling either a giant killer is an exaggeration.
What I mean by that is for someone new to the hobby, the Beyerdynamic DT531 and Senn HD25-1 are just an amazing deal in terms of price: performance ratio.
Yes they are bested by even mid-fi headphones in the $600 range. But considering the price you can find these for used, I'm not sure I'd recommend someone to 'upgrade'  and spend 500$+ an amp if they're happy with the sound.

Listening to John Coltrane - A Love Supreme I preferred the HD25-1 to my HD650 balanced system powered by a Beta 22/Lavry DA10.
The HD25-1 has a seriously sweet midrange for being as neutral as it is. Tonally accurate, yet easily heard in the music, almost 'highlighted'.
This mysterious midrange quality is it's greatest strength and the most stand-out part of the headphone followed immediately by it's tight, tuneful base.

Now for the negative part. Over time the closed in soundstage makes them less fun to listen to. It kind of builds on you over time and threatens to distract you completely from the listening experience.
But if you listen while doing other things, like snowboarding or skateboarding, biking, you don't notice this.

That's all I really have to say for negatives. For the right person, these are the ultimate portable and rugged, yet amazing sounding headphones.
If they redesigned the arc assembly so that the headphones folded outward when sitting on your neck, we'd have a new FOTM (flavour of the month) on head-fi.

Design/durability: They look professional. As for the build quality, these are certainly the most rugged headphones on the market. It is practically indestructible, and if a part comes to break it is possible just to replace the part itself (ear pads, cable, headband, you name it). They can be thrown in a bag and not be worried about. Designed to last a long time, if not a lifetime.
 
Fit/comfort: Average. Many complain about the clamping force of the HD25, but I find it to be okay after a few months using them. The headband becomes more loose and flexible, although it still has more pressure than on other headphones. Definitely not the most comfortable cans around, though.
 
Isolation: Among the best headphones when it comes to this aspect. They don't equal IEMs, but still have a superior isolation to most other headphones of its category. Good for outdoor use, even for air travel, unless you fly a very noisy turboprop.
 
Sound: Excellent, and still a reference despite the years. The sound signature of the HD25 is rather warm (V-shaped), and very revealing from bottom to top frequencies. The bass has a nice texture to it, and sounds fast and powerful. Mids are slightly recessed but they remain neutral, not colored. The treble is bright and slightly aggressive. Also, the HD25 have a good amount of energy in them, an almost dynamite-like punch that can handle any fast track. On the downside, soundstage is quite small although imaging is good. The HD25 provide an enjoyable, dynamic and polyvalent sound with a fair amount of details.
 
Bottom line: A classic that remains a classic, and a good bang for the buck guaranteed. Mine are 8 years old and still going strong.




HD-25 retrofitted with velour pads

I love my HD25-1 II Headphones. They are, in my opinion the perfect portable headphone. I am not a huge fan of on-ear headphones but I do quite enjoy them. The sound quality is addicting, they are easily driven by an iPod or iPhone and have quite a bit of low end (perfect for modern electronic music), but when put on a proper amp the low end levels out the headphone becomes much more accurate.
 
The only real problem I see with them is they have quite a clamping force and when put on with glasses can become very uncomfortable. I use them for a max of 2 hours.

Durable - replaced pads after two years - i use case supplied with phones for storage

I'll make this clear - the sound signature of these headphones will not blow you away. I was expecting a lot from these (after reading the many positive reviews) and when i first listened to them i felt a little underwhelmed.
 
We've all had that experience where we listen to a piece of music and think...meh it's ok - and then months later you're putting in your top 10 all time favourite list. Well i've had the same experience with these cans. I have grown to love them!
 
 
Design - They're lightweight, surprisingly portable and have a minimal look and feel. They can be used as DJ headphones due to their tilt cup design (the left headphone can be tilted away from the ear). They are also modular which means you can replace the parts if they ever go wrong.
 
Comfort - At first these things did hurt my head and gave me a bit of ear ache when listening for long periods. However after about a month of use, the comfort significantly increased. The clamping force became much less intense and i can now wear them for many hours.
 
Sound Quality - As i've already mentioned, the audio quality will not blow you away. These are a neutral set of cans with an emphasis on detail and clarity. The sound stage is lacking and some tracks can sound a little flat. At first i thought this was a bad thing, but soon i began to appreciate the purity in the sound that these headphones offer. Give them high quality audio and you will hear every bit of detail. What puts the icing on the cake though is the instrument separation - this is what these headphones do best and at very high volumes too (i sometimes DJ in a club where the booth is ridiculously loud and no matter what the volume is - i can always make out the low, mid and high without any bleeding of the sound).
 
Bass - A little more emphasis here, but they never overwhelming and sound punchy rather than warm
Mid - Clear and neutral in texture
High - Clear without sounding bright (not fatiguing on the ears)
 
These headphones are great for electronic music (house, techno, tech-house) and sound great with older flavours too (trance, progressive etc.)
 
Value - Not that cheap and even though they're modular in design, the parts are pretty expensive. However these things are build like a tank, so in my opinion they justify the price tag.
 
 
9/10 - i absolutely love these headphones and recommend them to anyone who is looking for a closed back design.

These headphones are great. I listen to mostly metal and have listened to Grado's mostly because of it, and these phones are really similar to the grado sound; I can see why people refer to these as the equivalent to a closed grado headphone. It's funny to me how different these phones are to the description of every other sennheiser headphones. Every review for the hd 600 or 650 talks about their laid back nature, while the hd 25's are anything but laid back. indeed, they are very forward, and for metal and rock, this is just what the doctor ordered. Bass-y music sounds great too, these headphones can really bring out the lower end of the sound spectrum. My only gripe with them is the initial comfort - it takes a bit to get used to the amount of pressure they put on the ears. After owning them for over 3 weeks now though I can say that I love this set. While its hard to argue with the portability of IEMs, these guys just sound so good I am willing to give up a little more space in my backpack when i need to store them.
 
Highly recommended, especially with the velour pads!

OK I've never reviewed headphones before but think that the Sennheiser HD 25-1 II are the perfect set to start out with, I really love these headphones, I think they look good and as for sound quality they are really great all round performers, great bottom end, good mids & good tops. I'm not gonna get technical with bright, dark, veiled, sibilant etc etc. I'm not good with all these terms, my ears tell me I like them, I wouldn't say they were sound perfection but I've yet to find a pair that could be described that way. I actually own/have owned many headphones, all of them have some kind of flaw. If I had to describe the flaw with these I would say they have a 'very slight screechy sound' but they do make up for it with their excellent sound quality & general performance, as I said before personally I think all headphones have some kind of flaw. I hope that my description doesn't put you of because I honestly think these are one of the better headphones available and out perform many at twice the price.
 
Nowadays I see more and more people wearing them in the streets & I think to myself these are people who care about how their music sounds, I got my first pair in the late 90's for DJ purposes, They are unbeatable. I've dropped them hundreds of times, the worst thing that ever happens is the ear-cups fall off, you just clip them back on again and your back in business, I've trodden on them more times than I care to remember, they've been literally ripped from my head when some fraggle went & got caught up in the cable (this has happened more than once). The cables are really strong. Durability wise these headphones are in a class of their own,
 
Comfort: They are tight but I wouldn't say excessive, they're not going to fall from your head, I always use them when I'm on my pushbike, safe in the knowledge that they are safe and secure. Sometimes I remove them for a few seconds to give my ears a break but in my opinion they're a comfortable fit, I like the way the headband separates, with a little bit of adjustment you will find the fit that's best for you.
 
As for portable audio once again I reiterate these are great headphones, they are of low enough impedance to perform well when plugged into an iPod. They are even better when plugged into an amp or my little Hisoundaudio Studio-V (DAP). Yes I do recommend them but I am biased because I totally am in love with them.
 
Bottom line... You can't go wrong with these headphones, they are highly sought after & have a high resell value, they make men look wise & women look sexy.

No review quite yet.

When I first received the HP25-1 II I was a little disappointed. They were tight on my head, to bright for my liking and bass was a little lacking. Right out of the box I was comparing them with my HD280s and felt that the 280s were better in every aspect except ergonomics. After a couple weeks of use I got used to the fit and started to notice the presentation was improving.
 
I actually fell in love with these headphones at CanJam 2010. Up till this point I was driving the phones with my ipod. I had read some reviews and an amp was recommended so I was on a mission for an amp. After many amps and comparing these phones with the best of the pack I can honestly say that they hold there own with the bid dogs when they have the right source and amplification. They have nice bass response and the highs were no longer overpowering. Overall I would say the sound spectrum is very well balanced.
 
There isolation is great when I use the phones at work or play. They stay on your head what ever activity you participate in, and when someone is trying to speak with you, you can easily pull them off to one side and listen. They have a rugged build and I suspect they will last for many years no matter what your activities are. Parts are readily available and the phones have a very simple construction so they are easy to work on and modify if you so desire.
 
Final thoughts. These Great little phones don't come alive until they have been burned in and are given a good source and amplification. The fit takes a little getting used to so give them some time.
 
Highly Recommended.

Good sound quality and good comfort. It is fairly lightweight but durable. The stock cable has some horrable mechanical transported contact noise (Some call it microphonics but microphonics is where mechanical vibration is transformed into electrical signal) so i replaced it with the HD650 stock cable. Yes i had to reverse the cups to make it fit.
I use it with a rockboxed iPod video and the RSA Hornet. Listening with crossfeed on i can listen to this combo for hours.
I listen mainly classical music. Opera, orchestral works, string quartets etc.
In my opinion, a closed can does not need to be perfect. i use a closed can to be isolated from outside noises but no passive closed headphone can isolate me for 100% so i will hear always hear some distracting noises
 
a great allrounder.
I do not really need a neutral sounding headphone since what is neutral nowadays? only my own ears listening to a live concert.
and my ears are not yours
 

The first song I listened to with the HD-25 (like with any new pair of heaphones) was Dizzee Rascal's "Bonkers". This is the one track that I know that feels like every audible and inaudible frequency is used in the bassline... It just surrounds you and therefore can be used as a benchmark tool to test audio hardware.
 
And boy was I convinced instantly, also the isolation is extremely good so all of that really set me on my way!
 
Definitely recommend!

My impressions is that these don’t sound significantly different than the cheaper SP version in terms of sound signature. The biggest difference is detail, more extended highs and smoother mid. If you didn’t like the SP version’s general sound you probably won’t like this either.

 

Comfort:
I personally don't like on-ear headphones that much because of sweat and heat reasons and this is no exception. These will keep my ears reasonably warm on a rainy day. Takes a little fiddling around to get a good seal. My ear gets warm over half an hour. The clamping force is just right, not loose or vice grip. 
 
Build:
Everyone says these are built like a tank and I agree. These headphones feel very solid and hard despite their plastic build. They will be able to withstand a good amount of abuse. I don’t suggest walking around with these in the rain though without an umbrella. Good headband construction. I like the two piece headband so it makes it easier for me to wear the headphone tilted back as the balance is better.
 
Isolation:
Not as good as my Westone IEMs but that is expected as these are on ears and not over the ears. If you’re a loud listener these are be ok on the bus or for walking around the city but for a really noisy subway train it might not be good enough as I found myself reaching for my IEMs.
 

High:

Sound somewhat rolled off. Cymbal hits decay fast. Snares sound a little thin and distant. As someone whose preferences are in a bright sound I would not say these headphones are bright as the HD558 sounds brighter to me and grados are far brighter than both. I would say in general these headphones don’t have any spike that would sound harsh; occasionally the upper range of female voices can sound a little scratchy and thin. I wouldn't listen to classical with these.

 

Mids are fairly forward even though it "sits behind" the bass often. Vocals sound quite close.  The mids sound smoother than the HD558 but in comparison it could sound more distant because of the bass presence. Male voices can sound nasally sometimes. I don’t hear any sibilance in voices. Midrange is pleasant to listen to most of the time, no harshness unless the recording was like that. HD25 does a lot good in this area with no glaring issues. 

 

Bass:

The midbass hump is prominent on every song and makes sounds sound warm. This can be good or bad depending on your preference. To me, it seems like the bass is the loudest part of all the whole frequency response. The mid bass is the body of the sound for these headphones. I notice it’s a little boomy as well.  These are good headphones for DJs as songs from deadmau5 or music in dubstep and trance genre will shine as the pacing of bass beat is very suited for these headphones. These are the headphones that your pop loving friend might like as well. Music with rhythmic repeating bass beats goes well with the HD25. Bass reaches depths that surprised me for the size of this headphone.

 

Soundstage:

Fair for a closed headphone, doesn't sound significantly wider or deeper than my Westone UM2. No artificial wideness or anything like that. I would not use these for gaming as pin pointing can be hard. I never get the feeling the sound is coming from outside my head but quite the opposite; the sound is coming from inside my head and stays there. A closed headphone like the ATH W1000 is much closer sounding to an open headphone than HD25 but that’s another discussion.

 

Detail:

Don't expect globs of micro detail but enough for enjoyment. You can hear nuisances but they are more blended in and again, the bass makes it harder to hear these small details. I wouldn't use these for mixing or for critical listening. Separation is reasonably acceptable but plucking of string instruments are not as distinct as grados for example.

 

These headphones are fun to listen to. If you are very critical of detail these are not for you. This is one of the closed back headphones everyone talks about so I figured I'd try it. These sound somewhat like Westone UM2 with a smoother midrange, more bass and midbass tossed in and less dry sounding. I will stick with my UM2 because I think the bass is a tad much for me but otherwise I can see why these are popular.

Good value for the use I get out of them professionally and personally.. A great all rounder Can and they make my ears happy

Summary: These headphones give an accurate picture of what the producers had in mind when they mixed their music because they have a well-balanced, present, but not over-powering bass.
 
Songs Used for Listening/Critiquing:

1. Stuck on You - Michiko
2. Unlike Any Other - Jeremy Ellis
3. Garden - Totally Enormous Extinct Dinosaurs
4. Basically, **** You - Deru
5. Flashlight - Parliament
6. Creator - Santigold
7. Petrified - Fort Minor
8. Jamba - Tyler, the Creator
9. Ballad of NGB - Stateless
10. I'll Never Leave You - Rogue Wave
11. BloodStream - Quartet Session - Stateless
12. Blue Ridge Mountains - Fleet Foxes
13. Sunburn - Muse
14. Rhino - Solander

 
I know that headphones are truly the best consumer audio market right now, and that's cuz I said so.
 
Just kidding.
 
But seriously, not a day goes by where I don't see at least 250+ people with headphones or earbuds on their heads, listening to these ridiculously leaky headphones that tell me more about their music taste than anything else.
 
Firstly, I think these headphones are quite something else. I can't put my finger on it exactly, but I know that they are amazing. Honestly, words can't describe the satisfaction these headphones bring to the table. I don't think I could describe the sound quite like others do (spacious soundstage, sweet treble, warm mids, supported bass, etc). On a side not, I work in the food industry, specifically coffee, and every day I have to work with coffee from Intelligentsia, people who describe their products with fluffy descriptive, pastoral, and picturesque diction and abstract syntax; I am not that kind of guy. I prefer to describe everything simply and with ease of understanding, so here goes.
 
These headphones are good. They get the job done. They are utilitarian. They are affordable. They are the PERFECT consumer product because they do everything that a consumer needs.
 
I own a pair of Sennheiser HD595's as well as Ultimate Ears Triple Hi Fi 10v (or something like that). I have also listened to the Senn. HD598, HiFi Man 500s, the Senn. OCX800, and a variety of Beats, Monsters, and other things. Of those, the HD598, HiFiman, and the Ultimate Ears were my favorite because they had noticeable clarity. They sounded good and didn't give me fatigue. I'm sure some have noticed that when listening to bad headphones, subconsciously or not, you get tired of listening to that music. I mean, if you listen trap music or like Blink 182, MUSE, and other high-gain songs that have massive compression and gain boost on the final mix, then duh of course you'll get fatigued, but I'm talking about Dave Brubeck, Kronos Quartet, and the Hilliard Ensemble. Listening to Stacey Kent's beautifully soft voice is tiresome when I have ****ty headphones on because those headphones don't sound natural, at all. The headphones that I liked were all natural-sounding headphones, with authentic sound that comes with quality engineering and technology.
 
Then come in the HD 25s. It is an amazing product because it sounds just like all the other headphones I listed above but with more bass. Why is that important? For me, it's very important; my mama always loved Earth, Wind, and Fire, Parliament, Chic, etc. and my dad loves Led Zeppelin, Deep Purple, Bread, America, Sultans of Swing, etc. My uncle loves Jimmy Hendrix, Beethoven, and Bach (weird mix right?), and I love electronica, rhythmic world music, and folk music. With all that exposure (and rest assured, I listen to all of those genres on all of my headphones, all day, every day), the one common factor between all of them, from Bob Marley to Aphex Twin, is bass. This is pretty obvious, considering the fact that bass notes hit harmonics with higher notes, immediately beefing up the overall density of sound that is produced. For example, when I was in a band and played one of my songs, I'd always incorporate a melodic bass line that runs against the upper register instruments (like the piano), and it never sounded thick or dense, but when the band played solid, unified chords, I was so astonished how much of a difference it made. This subtle, meticulous balance of bass and other frequencies is hard to accomplish, and that's where these headphones shine.
 
The bass on these headphones are not overpowering to the point where you can't hear other instruments, but they aren't thin like the HD595 to the point where Fleet Foxes sound wispy. They are perfect. They make the MUSIC sound BETTER. Now, I am not a pro audiologist, audiophile, whatever you wanna call it, but I can appreciate a well-balanced, supporting, not overwhelming, not nonexistent bass with a low range that goes all the way down to hit the sub-sonic frequencies in Tyler, the Creator's "Jamba," and these headphones are remarkable.
 
This is, again, my opinion however, and I think that is an important fact to consider. Some people like powerful bass, some don't, and I am neither of those, so consider my recommendation with a grain of salt. Furthermore, there is no such thing as "best" headphones; that's like saying there is such a thing like the "best" car, "best" steak, or whatever. It doesn't mean ****. Yet I can't help but appreciate how affordable these headphones are; they aren't, say, as cheap as some other headphones, but what you pay for and what you get is remarkable. On top of that, maintenance is super easy! Cables, ear cups, and other parts of the headphone are easily replaceable, a feature I love.
 
The worst part about these headphones? The looks. See, I think these headphones should be the standard headphone for everyday consumers; it gives accurate pictures of what the producers wanted to make in their labs, so you see an honest, untampered musical idea. Beats, for example, have a stronger emphasis on bass, and so every song will have a bass emphasis, even if the producer didn't want one. But they aren't pretty, and they aren't marketed well. They do really well with professionals, but I have such an itching to have my friends all listen to these side-by-side with their headphones just to open their "eyes" to what's out there. Clamp force is strong, but if adjusted well, it's fine (plus, a good seal on the ears = better bass).
 
Regardless, thanks for reading my ridiculously wordy, sarcastic, and boring review (just kidding, my reviews are the BEST). I recommend these headphones to anyone who's looking for something that is affordable, accurate, and eye-opening.

Happy Listening!

 

Specs​

 

 
I'm still burning my 25 in (and I do believe in burn in - partly because NwAvGuy says that he does, partly because I *thought* I noticed a difference with phones I burned in left connected to my PC when I picked them up a week later) but already I'm in love with them. 
 
They're often cited as being a superb rock phone and having a rather Grado-ish signature instead of the laid-back Sennheiser house style. I'm going to eschew words like "forward," "dark, aggressive" etc because they're meaningless, subjective, and subject to change by EQing. 
 
Instead:
 
- You can make the 25s sound bassy, mid-range dominated or trebleish by using your EQ. These things are very responsive to EQ!
 
- I literally heard things in tracks I'd never noticed before. Tracks I've listened to for years, often using my supposedly detail revealing Ety HF5s.
 
- For those who don't know, prAT! (I think I have the capitalization right - I didn't know the word yesterday myself, other than its English slang meaning) is a the ability handle sounds with lots of attack - ie sharp beginnings and ends - convincingly. So drums need prAT! big time, and human voices and acoustic guitar much less so. Electric guitar otoh needs it quite a bit - and so does piano. (Imo.) The 25s excel in prAT! Drums and electric guitar sound better than I've ever heard them before. And I've just switched to a Ben Folds album and the piano sound amazing.
 
 
- Soundstage is there, but it's ***tight***. You don't just feel that you're on stage instead of an auditorium seat (as people say of Grados) - you feel that the band has formed a tight cluster around you, and start wondering why can't smell Gillian Welch's breath and why you're not getting sprayed with sweat by the Replacements. You remember that story about John Cale beheading a (dead) chicken on stage and wonder if the blood will wash out of your clothes. The instruments separate out magnificently, and you have a feeling of intimacy with the performance. I love it - but you might not.
 
I didn't test with orchestral classical music - my classical tastes are more for piano and chamber music. If the Eroica is the sweet spot in your listening tastes, then I can imagine that the 25's presentation might seem rather bizarre.
 
- Vocals sound amazing. Ms Welch really does sound like she's standing beside me singing directly into my ear. From a range of about 5cm.
 
- I've heard people say that certain high end phones won't tolerate bad recordings and sound worse with them than cheap phones would. I have no idea if this is true, but to my ears it isn't the case at all with the 25. I have an awful bootleg concert recording of the Replacements and the 25s, in cooperation with the J3's EQ, let my ears cut through the fog and murkiness to hear hidden detail. The result was a recording that sounded better than my studio albums did yesterday - you can still hear a lot of the sonic flaws, but the good stuff dominates and that's what matters. 
 
- I bought the 25s looking for phones that would make music sound as exciting to me as my old Mission 70 speakers did (these things were real killers for their day...) They've done everything I hoped there, mostly by way of that prAT! thing, but they've also revealed so much I wasn't hearing before that a lot of music has changed for me - I can see myself buying a lot more jazz, for example. And some later Clash recordings have just opened up and revealed magnificent textures that I never suspected they had - stuff quite at odds with my assumptions about them.
 
- Comfort Mine are fresh and the ear clamping is a little hard - I'm feeling some real pinching at the top of my ears. I understand that it would be less if I swapped to the velour pads, and that the band will become a less aggressively springy in time. At the moment it is a small price to pay.
 
- A nice feature is that the band consists of two arms. You can adjust the gap between these from zero to lots - the idea is that the twin arm design will cradle your head keeping the phones on under all conditions - these things are designed for news pros and DJs.
 
- Useful hint picked up from the net: you're supposed to set these so that they're slightly loose and then tighten the fit by widening the headband split.If you do this they're much more comfortable - I can barely feel mine on my head now, although they've also had 12+ hours of wearing to break-in.  If you're a DJ or in a TV news team, then someone will tell you this, I suppose. But for everyone else Sennheiser  really should have included a manual...
 
- These things have a rep for toughness - news people and DJs use their gear hard and they survive it for years. And because they're meant for pros, all the parts are user replaceable - you can buy every component from Senn and swap out broken band or a driver for a fresh one.
 
!!!IMPORTANT WARNING!!! 
There's one spot on each side of the band where the cable running between the ear cups can get trapped and damaged if you completely close the two bands together. There's a notch to prevent this, but the cable might not stay in it. If you're going to repeated close and unclose the bands completely - which is pointless - then you will want to watch this or add a dab of tape or something.
 
 
- Sounded great on the Clip+ and J3. I *think* they sound better on the J3, but I didn't do an ABX test and really don't trust my own feelings on this sort of thing. There was no problem getting them loud enough on either player. I keep them at about 22-26 of the Cowon's 40 level volume control.
 
 
 
- Looks: Industrial in the functional rather than the designer sense. These things are designed to blend into the background of TV news and sports broadcasts.
 
But... the 25s are *very*  customizable. You can change pads and cables for coloured ones, and even paint the band and shells. Or you can buy some amazing pre-customized phones from http://www.customcans.co.uk/
 
The owner of Custom Cans posts on head-fi as jfunk, btw. They also sell coloured ear cushions and what have you - including from an ebay store. They're based in the UK, but I think they ship everywhere. They customize other several phones, but the 25 seems like the core of their business.
 
- I've avoided giving numerical scores but for those who must have them, choosing some widely known comparators: if I gave the HF5 a 5 for sound quality, then the EPH100s - which are widely being compared with some of the best IEMs around - would be a 6.5 to a 7 and my Superlux 668Bs a 6 or maybe a bit more. The 25s would be, oh, a 9.5. Maybe they'll be a 10 when they're burned in. But I'd be the last person to deny that a lot of what makes a good set of phones is subjective, so ymmv. 
 
***Postcript***
- The HD25-SP has different drivers and a simpler headband; I've no idea how close it sounds to the "real" 25
 
- The Standard edition comes with a (cheap, unpadded) bag and two pairs of cushions - pleather (fitted) and velour
 
- The Basic edition comes without the bag and velours
 
- The Adidas is a slightly prettified version of the standard edition.
 
If I  was buying again I'd go for the Basic and use the money saved to buy funkier velour cushions from Mr JFunk - he also sells what looks like a very nice bag. Or I might go crazy and buy one of JFunk's special editions.
 
Finally, as so often, UK buyers get an awful deal on the price of 25s compared to Americans. So if you're in the UK and making a trip to the US, you might put buying a pair of 25s on your to-do list. But also, as mean and obsessive about US-UK price differences as I can be, I am ***really*** glad that I bought these!
 
- The estimable Mr JFunk of Custom Cans has provided a guide to tweaking the 25s acoustics here:
 
http://www.head-fi.org/t/590995/some-diy-mods-for-the-for-the-sennheiser-hd25-1-hd25-13-hd25-c-hd25-hd25sp
 
..And a guide to painting them here:
 
http://www.head-fi.org/t/573845/heaphone-airbrushing-guide-with-lots-of-pics
 

I've owned 2 pairs of these headphones over the past 10 years so feel I've gotten to know them pretty well. Apart from the cheaper SP version these are the only decent headphones above a budget level that I've really tried.
 
Looks
 
I don't think this headphone is for the fashion conscious but they do have a cool look of its own in an industry standard geeky DJ kind of a way.
 
Durability
 
This is a mixed bag for me although maybe it is harsh to complain about a pair of headphones that last so long. Overall they are pretty indestructible and I regularly take them to the gym and put them in there and take them everywhere without a second thought. You don't need to treat them nicely for fear they will break. I've never had any problems with the headbands or drivers. However there is a fundamental design flaw with this product that has occurred with both of my units and is well documented by other users. After a while (often many years) one of the cups will develop issues with intermittent sound requiring you to wiggle the connector cable to try to make it work again on a regular basis. The problem is that the spring inside the ear cup which the headphone connector is placed inside become faulty. If it wasn't for this i'm pretty sure they would last forever which I doubt sennheiser would want - they want you to buy another set. I'm sure it could be easily remedied if they slightly altered the design. 
 
 
Replacement Parts
 
It's a positive that so much of the headphone is user replaceable. However, although readily available, they are also ridiculously expensive such as the £40 price tag for a new cable.
 
Comfort
 
There are definitely not the most comfortable headphones out of the box. They exert a significant amount of pressure on your ears although the do loosen up after a time and become comfortable. That coupled with their lightweight design does mean when they have broken in I do find the comfortable to wear for sustained periods. 
 
Impedance
 
These do go very loud when using a dj mixer, a sound card or my macbook pro laptop. When using portable devices such as android phones I find that they are only just loud enough for me so I need to push the gain of my music app to its maximum before distortion to get the level I desire. They are loud enough to use but I would prefer quite a bit more headroom so I would only half recommend them for portable devices. Something designed to be so portable and durable really should have been updated to be more compatible with phones and portable music players.
 
Sound
 
I do like the sound and they offer excellent isolation. They sound exciting but a bit harsh in the highs and boomy in the bass. They have almost a dark sound and sound very full and not at all tinny. I wouldn't call the neutral. They are great for djing especially since the kick is emphasised in the low mids but for producing I'm not convinced. When mixing with them I find I tend to end up with mixes that are dark in tone, overblown in the bass and quite dull and lifeless in the highs. I really find it hard to make informed decisions about what is happening in the low end and mix the bass and kick particularly. Maybe high end harshness is part of the problem that leaves me with dull mixes. 
 
Conclusion
 
I need to replace these now and I am tempted to get another pair because they are very versatile in that you can use them for djing, sport, sound design, and to a limited extent mixing. They are also durable, lightweight and comfortable after a while of breaking them in. However I can't help want more from them - a pair that are more comfortable from the outset, that I can reliably mix on and that don't develop a fault after so many years with the ear cup connectors. Maybe I should buy these for recreational/dj use and then another pair for mixing as I could end up disappointed trying to improve on them.