Sennheiser HD 650 Headphones

The HD650s have been out for many years already and became a reference point to compare with other headphones. Although not the best headphones, they can still introduce you to the world of high-end sound, as long you provide them with proper amping.

I moved from IEMs to full sized headphones, and the HD650s were my first real investment. My first "real" audiophile big can was actually the Audeze LCD-2s, but I never had proper amplification back then. As a result, I never experienced what the LCD-2s could actually deliver. I ended up selling my LCD-2s and then going back to IEMs, all the way until this year when I took the dive and tried to buy the safest, most solid cans set I could. I went for the most famous, solid buy and went hunting for the best amplifier match. This, of course, led me to the Sennheiser HD650s.
 
My chain ended up looking like this:
 
Foobar2000 with WASAPI Event, FLACs > Schiit Modi DAC > Bottlehead Crack + Speedball Upgrade (with Tung Sol 5998 Tube) > Sennheiser HD650s (Silver driver)
 
THE STAR-RATING
 
I have been beating myself up over whether to rate the HD650s with 3.5 stars or with 4. If I really could choose, it would be a 3.75/5. However, I am marking in a very difficult manner; I have tried out a handful of good headphones and so it would take a lot really wow me. A 4-star rating would be a "wow" but with a few reservations here and there. So, a 3.75 is a very good mark; it is just short of a "wow." The details with the little green bars are a little more informative of the way I feel about the HD650s (EDIT, the green bars seem to be very inaccurate when I save the post. Instead, here are the scores: Audio Quality (B+), Comfort (A), Design (B-), Value (A+).) With that in mind, let me expand on my experience with the HD650s.
 
FIRST IMPRESSIONS
 
At first, I thought the HD650s were absolutely dreadful. The bass was extremely floppy and bloated. The lows were absolutely non-existent. Treble and highs were slightly tinny, but mostly just very unrealistic and slower than a snail (it seemed like there was long decay on treble and highs). I was very concerned and posted in the HD650 appreciation thread with my impressions; I wasn't sure if I just didn't like the sound, or if there was something wrong. And, given that the Crack is a DIY amp, I also went on the Crack forums to try and figure out if there was a serious mistake. 
 
Well, there was a big mistake. The headphones and the tubes in the amplifier were not burned in. I'm a very scientifically inclined person, and so I have always been very skeptical of burn-in. But after my experience with my setup and burn-in, I am now a 100% believer. The difference was so enormous that I am not sure how anyone could deny the existence of burn-in, at least for tube amplifiers (I don't expect it to be very real when it comes to solid-states) and dynamic phones like the HD650s.
 
After about 30 hours of burn-in with pink noise and various music at slightly higher than listening volume, suddenly the lows appeared. The bass tightened up tenfold, and the treble lost its sibilant ring. The mids, for the most part, sounded the same, though they were never really atrocious to begin with. 
 
THE DESIGN & COMFORT
 
The design of the headphones is simple, but they look professional. The biggest problem I have with the HD650s is their construction material. I was very disappointed to find out that the headphones are made out plastic, and plastic all over. This doesn't mean that they're flimsy, but I wish there were more metal on the headphones. If you look at the picture of the HD650s on the HeadFi reviews section, they look almost metal. The reality, however, is that they're almost entirely plastic and a lot lighter than you expect. The headband comforter is also not premium; for instance, the headband on the HD598s seem higher quality.
 
The clamp force on the headphones is great. It's a little strong, but it's better to be strong and loosen over time than be loose from the get-go. The earcups are quite large and will fit around even the biggest of ears. 
 
SOUND QUALITY
 
My reference point has primarily been my experience with the Shure SE535s, Earsonics SM3 V1s and the Westone UM3X in-ears. In terms of speakers, a set of JBL LSR2325p studio monitors. The rest of my can experience has been with lower end headphones (like the ATH-M50s), Shure SRH750DJs and a bunch of lower end Sennheisers. Indeed, these comparisons are not always fair; each is a different class and will present sound differently. With that in mind, I will try to present my impressions as transparently as possible.
 
GENERAL STATEMENT
 
The sound of the HD650s is really good; however, I would hesitate to call them spectacular (though they are spectacular to people who allegedly enjoy the sound signature). When people say that the HD650s are laid back and mellow, they really are not kidding. I always had a hard time imagining what they meant. The closest thing to "mellow" I could think of were the Sony MDR EX1000s, but the Sonys are more "romantic" than they are "mellow."
 
What I found "laid back" and "mellow" to mean is that nothing is really forward or present with the HD650s. Some people really value this aspect of the HD650s. For me, it did not really hit the spot, but I can respect and appreciate it regardless. Nothing really stands out with the HD650s: everything sounds good, but nothing really jumps out at you as being their focus, or even as being superb. This makes for a mellow and relaxed sound. You will never fatigue listening to the 650s because nothing is being pushed on you. With the 650s, the music is presented gently to your ears, and it makes very good for "just listening" and going about your business. It's probably the best headphones to have on while casually listening, but I believe you will be moderately disappointed if you would like to really close your eyes and feel lost in the sound or if you have high expectations about being swept off your feet. This is because with the way the HD650s present the music, you just know that the music is being played at you and that you're listening through a pair of headphones (albeit a really good pair).
 
THE BASS
 
The bass is very, very good. I just wish it could be 10% punchier, but it does a very good job. However, the HD650 bass really depends on the track. On well mixed and mastered tracks, you will get a very nice bass. It is very controlled and, for the most part, feels "just right." It's some of the best bass you'll be getting if you're not a basshead, and if you're listening to music and don't explicitly want to be jumping around and dancing. I really, really enjoy the bass for any kind of listening except for dance music; it does its job fantastically. However, I believe if it were just 10%-15% more punchy, the HD650s would really be brought more to life. Then again, the phones are supposed(?) to be laid back. It's like being hit with a harder pillow; it's not too soft, and it's not too hard. It's controlled, disciplined and almost at the perfect line between whooshy and punchy.
 
THE LOWS
 
I believe the lows are the absolute best part of the HD650s. If you get a good recording, the lows are just magnificent. Bass guitar sounds just wonderful on these headphones. It sounds very, very natural and even electrifying at times. With the right racks, the lows really carry the track forward and keep you slightly bobbing your head or tapping your feet. This is really where the HD650s shine.
 
THE MIDS
 
I think I have to admit that I'm a little mid-obsessed. If you look at my previous IEM collection, you can tell that I bought IEMs I believed would bring me great mids. The HD650s, although it might be unfair because of how much I like mids, did mids just fairly. I mean, compared to anything else the average person has heard, they certainly are very good. But I do not think that the mids are as well refined as the lows. Keep in mind, though, that some people like the mids the way they are and don't like forward mids, so it is all up to you. That said, here are my personal thoughts on the mids.
 
1. I believe the mids could be brought a little forward. Even if the headphones are not supposed to be uber mid-centric, I believe the mids are just 20-25% off the mark in terms of their closeness. Sometimes a track that is normally really engaging just isn't on the HD650s, and it's because the mids just aren't present as I believe they ought to be. (Then again, personal preference plays a big factor.)
 
2. The mids could be warmed up a bit only because voices didn't seem realistic or natural. Compared to what I've heard on the SM3s and especially the Shure SE535s/530s in terms of vocals, the HD650s made vocals sound like they were just being played at me. I didn't feel like I was being sung to, which makes me very sad because I like it when Taylor Swift whispers into my ear.
 
3. Some people argue that being too forward on anything isn't "natural." But I don't know what is more natural than hearing a singer as if the singer is speaking to you, given that's what it sounds like in real life (the epitome of natural). I could not feel my singer's breath, and I knew that there was a mic between me, the singer and the music. If you've ever heard the SE535s, that's how vocals ought to be done; they are so lush, smooth, caramel and real that you sometimes get goosebumps from good recordings.
 
4. If you're not vocal-mid focused, then the mids will do just fine. In fact, guitar sounds great through the HD650s. B.B. King sounds great on the right recordings, as does distorted guitar in classic metal bands (e.g. Judas Priest, Iron Maiden, etc.) and groups like Paramore. However, the vocals just isn't this headphone's strength; I tried Grammy winning engineered albums and very well reputed vocal albums (including jazz vocals, etc.), and none of it stood out as being outstanding. It's just a fair contender.
 
The mids, as they stand, are pretty laid back. You get fairly good detail, but there isn't a lot of body to the mids. This is perfectly fine for instrumentals, orchestras and a lot of other music, but it is not good for very vocal centric music. The 650s are still quite textured, and so the mids aren't by any means bad. Guitar, especially in classic metal and rock, sounds great. I love guitar through these headphones. However, despite what some other reviewers might say, coming from someone who has a history of hunting for mids, I do not believe the 650s hit the mark on mids if you are someone who listens to a lot of vocals. For instance, running Adele, Taylor Swift, Hayley Westenra or lower voices like John Mayer or Diana Krall(sp?) through any of the mid-kings would be a reliable hit. However, none of these really stood out with the HD650s.
 
This is all to say, however, that "Kind of Blue" by Miles Davis sounds absolutely extraordinary on the HD650s. In fact, I believe it is the absolute best recording I have heard through these headphones; it has yet to be bested. The saxophone is breathtaking. But Miles Davis wasn't known for his vocals, and none of the tracks offer any. But that's why the HD650s did well with it.
 
HIGHS AND TREBLE
 
With my first Raytheon 6080 tube, there was a lack of clarity up top and in the treble in general. Switching over to the Tung Sol 5998s, the highs and treble came out. The highs are never sibilant, but aren't very energetic either. Overall, they are highly satisfactory for most purposes, but I believe things would really come alive or be taken to the next level if you could squeeze another 15-20% out of the HD650s up top. Then again, the HD650s aren't known for an energetic or hot-top end. 
 
The HD650s are not very analytical, but it is enough for you to understand a bad recording for a good one. However, it is forgiving enough to keep everything tolerable, even if not blissful at all times. I don't really find myself complaining about the treble or highs, but I also don't find myself being blown away by them either. The "air" of the HD650s lends great to shimmery sounds, however; it kind of sparkles just enough for you to smile.
 
SOUNDSTAGING & OTHER
 
The soundstage of the HD650s is all right. Some people have described the sound as "three blobbed" and I understand why that would be said about them. The HD650s sound like they have a medium-small room soundstage. The instrument placement in the recordings is good, but I sometimes crave that BIG sound. I thought the HD650s would deliver on that front, but they really aren't that big. The suondstaging is by no means bad, but again not spectacular. The sound is not congested, but you can tell that the music is being played through headphones, rather than feeling like you're there with the music.
 
Instrument separation is not particularly high (but that doesn't mean the HD650s lack a lot of resolution). I think the 650s like to give one coherent, gentle sound rather than ripping everything apart like the UM3Xs or completely punching you with a tidal-beam of sound (as on the SM3s). I think the level of resolution is perfectly fine. I think it could use a nudge more just because, but there is nothing negative to be said here! But this is a good segue to the next point:
 
VALUE
 
You can nab a mint pair of HD650s on the secondary market for extremely cheap. Low to mid 300s before shipping. That is an oustanding deal for such a solid pair of headphones. I bought a winter coat more expensive than my HD650s today, which just helps put everything in perspective.
 
If you noticed, most of my criticisms were wanting 10-25% more out of everything. But I suspect that's what is supposed to be delivered by the next level of headphones (HD800s, LCD2s, etc.) which cost a lot more. For the price, the HD650s are very well justified. And, the truth is, the HD650s should be a staple of every headphone collection (if you can afford to keep it)!
 
CONCLUSION
 
Overall, a very good headphone, but seldom spectacular (except in the lows if you hit the right recording). The headphones sound laid back, and maybe that was Sennheiser's goal. But, if I dare say, perhaps it sounds laid back because it does everything just "well," but never anything more. If you took the 650s and somehow could extract that extra 10-15% from it, it would be absolutely outstanding. The phrase "So close ... yet, so far away" describes my HD650 experience quite aptly.
 
The lows are its greatest strength, followed by the bass. The mids leave you wanting a lot more if you listen to vocals, but can deliver from time to time if you like guitar or non-vocal music. Dance music and electronic music, however, is really off the table. Electronic music is what I listen to the most (not anymore, though, just because of my setup!), but I just don't think electronic music fits well with the HD650s because electronic music is, by nature, a high energy genre, and the HD650s are anything but energetic. They are not energetic anywhere along their sound, and I think that is both what makes them so charming, but is at the same time their downfall.
 
The HD650s, by being so close yet so far away, is just a great, solid listen. It really is the introductory audiophile can par excellence. It does everything well, but not well enough so that you know there is for sure better out there. If you could just push that extra bit of work out of it, the 650s would really be stellar. But, hey, maybe it's just my amp and DAC; perhaps you could get the extra work out of them if you hooked up some multi-grand amplifiers... Then again, if you're fooling around with something like a Zana Deux, Leben or Wine Audio, you probably shoudn't still be listening to the 650s! 
 
Very good, but seemingly always a tad short of spectacular. 

Ok, so this review isn't going to be nearly as long as my first one. There are just a few things I want to address with these coming from much cheaper setups.

First, the build quality.
These seem built very sturdy. The stock cable is phenomenal and I really wouldn't see a reason to "upgrade", especially with so much of the controversy surrounding the actual audible differences. The only minor complaint I have buildwise is how the hinges when swinging horizontally sometimes *click* and the action isn't smooth. It's not a very good feeling and it makes me think that they're going to break or something. 

These do clamp on your head but I am very used to that sort of thing, doesn't bother me one bit especially with these comfy velours. these are by far the comfiest headphones I've worn. They are heavier but it isn't an issue because the padding is sufficient.

Now about the sound. Coming from studio monitors, I notice that it's a lot smoother. I was shocked when I first heard it. Coming from a bright headphone and hearing so much about that "sennheiser veil" I thought it would sound a little muffled at first. Nope. The treble is lovely and never overextends, a problem I sometimes had with the superlux.
I am also surprised at how well balanced the bass is. It is never overpowering, always modest but audible. These have a slight warm tilt but it makes these sound very musical imo. Reminds me a bit of my m50 yet with less bass emphasis and faster with better separation. 
By far though, the best thing about these are the improved mids. The mids are so smooth. They are more forward than the superlux, and more natural than the m50. It's not necessarily that I "hear" more with the hd650 because tbh I don't think I really do. It just sounds a lot less distant and disconnected from the other frequencies.

EDIT- I feel like these will be the last headphones I buy for a long time. Unless it's just for fun to compare I don't think many can oust the hd650. This is almost sonic perfection, or as close as you can get to it without humongous over-the-top setups which may give a smudge of more detail and clarity. But ultimately, the music is what counts and it's never been this enjoyable before. 

Use to think the HD600 was the best. When connected to my Asus STX  it is better then the HD650. (March 16, 2017 update)
 
Then I bought a Dark Voice headphone tube amp from Mass Drop. The dark voice is so much better with the HD650. Rolled a few tubes and the HD650 sounds excellent. The HD650 really does scale with your equipment. I do not even listen to the HD600 any more. With the dark voice the HD650 is smooth and crystal clear but you also know you are using an analog sound. There is no "dark veil" with the dark voice.
 
 
I have:
SR-60, Sr-80, HD555, HD595, HD600, HD650, AKG Q701, Bose QC 15, ATM-50S, Ultrasone HFI-780.
Least favorite: HD555 (boring and Muddy) and Ultrasone 780 (Sharp and shrill-Maybe needs more break in)

These have an addictive eq curve somehow as they emphasize just those aspects of the midrange in the same way that Doritos has been intentionally researched to cause one to eat the whole bag... it's no surprise how popular they are..... recommend for those who just want a headphone experience, especially if he/she listens to modern music. For classic music, meaning that which was made circa 1960 to 1990, these are Flat and unnatural sounding though. Lots of folks seem to think these are reference in terms of eq and even moreso for the 600 and on paper it looks like they are. In reality, reference is more than a good balance of eq. Reference has to 'refer' to real world sound and real world sounds of strings and percussion in particular do not align very well with what I hear coming out of the 650/600. But if you don't know or care about such things, these will rock your world. Spend hundreds of $ and many months in finding your favorite sound augmenting amplification, sit back and let the sound take your worldly cares away.

Awesome headphones. Perform a lot better with good amplification. Good for almost every genre of music. Bass response is already good, can get even better and tighter with amp. Extremely lush sound signature. You can spend hours with it without getting fatigued by sound. Treble, though sparkling, sounds bit rolled off but that's how they can be so relaxing to keep listening forever. Only area where these headphone leaves you feeling want more is build quality. Plastic used is strong but at the price tag doesn't justify the use of plastic.I really liked to see what Sennheiser done with Momentum they could have done similar with looks department of these headphones after all its almost 10 year old design.

If you can change the cable of HD650. You will find that HD650 is the best value headphone in the world.

The praise that has been heaped upon the Sennheiser HD650 headphone is something that probably every headphone OEM envies. The HD-650 is nearly a decade old and yet is still viewed by many as a top tier dynamic, worthy flagship, and is the benchmark that many measure price to performance ratio against.
 
I personally was cruising along quite happy with my set up… Running almost exclusively between Denon D5000’s and Ultrasone Pro900’s. I felt I had the best of both worlds. Since I love the visceral impact of good bass in my music, these two pieces seemed to be perfectly tailored to my listening habits.
 
The Denon gave me a little more reasonable treble energy and a little less sibilance when I needed it for something more complex and diverse. While the Pro 900 gave me that sub woofer for your ear feel that just flat out slams your ear drums. With a decent DAC/ desktop amp set up I am usually able to apply a 6kHz to 8kHz cut to smoothly equalizes the sound to eliminate that “ESSS” sounding ear razor that the Pro900 is so infamous for.
 
However somewhere along the way the constant gushing over the Sennheiser HD650 got to me. Specifically Mike from Headfonia repeatedly claiming that it was the ultimate king of bass impact…. He never said king of bass quality, quantity…. He always spoke of the HD650 in terms of “Impact”.This should get just about any hard core and well funded bass head’s juices flowing and so I began looking at the viable options for acquiring this apparent low frequency giant. And so after parting ways with most of my portable equipment, I was flush enough with cash to purchase my own set of the venerable HD650.
 
I will start out by saying that because of all the talk of the ‘luscious mids’, smooth highs and world class low frequencies my expectations with this headphone were near off the chart…. I have since done the same thing with my first attempt at the  Audeze LCD2. The LCD2 albeit a very good headphone, was so overblown in my mind that by the time I actually listened to it, I was disappointed. That had far more to do with my overblown expectations than anything... because second time around... being aware of how much darker the LCD2 was than its Hifiman counterparts.... I have found a place for the LCD2 in my stable.
 
But by the time the Sennheiser headphone had finally arrived, it was competing with dare I say unrealistic and extreme expectations and was pretty much behind the 8 Ball from the start.
 
Build & Design
 
The Sennheiser HD650 is certainly a dated design. There are dozens of headphones on the market in the same price point that are better dressed. Most $500 headphones have premium materials such as aluminum, leather and wood worked into the build. The Sennheiser headphone is almost exclusively plastic. It is a shiny, cheap feeling plastic on virtually every exterior surface sans the grill, ear pads, retainer ring and bottom of the headband. Detail items like the "Left" and "Right" indicators are simply cast into the grey plastic.... This build quality seems unfit for a legacy flagship.... Obviously its been a long time since this headphone was brought to market and Sennheiser was working in the pre-Beats era, long before headphones were valued as a fashion accessory and long before OEM's thought they could bring flaghips to market with price tags north of $1000. Sennheiser's HD800 and HD700 show they clearly can design a top tier headphone both in sonic character and design quality, but the HD650 is still asking $500 USD and doesn't give you a warm and fuzzy out of the box once you've got it in your hands, at least it didn't for me.
 
The headphone is extremely light. Many in the community would give it points for this and they are certainly entitled to their opinion. However I personally see this as a demerit. Speaking strictly in terms of assessing an items value from a subjective/ aesthetic viewpoint, the Sennheiser headphone appears to be made of cheaper, less durable materials. I am not going to strain my neck if a headphone is north of 400 grams. The Hifiman HE400 weighs in at a hefty 440 grams and is perfectly comfortable to me, the Denon D5k weighs in around 360 and is probably the most comfortable headphone I've ever worn. If one is spending $75.00 on a beater set of portable cans, an expendable gamer headset or a cheapie like Superlux or Porta Pros (of which I am a fan)  then by all means they should be and can be as light as a feather and made almost exclusively out of plastic without raising eyebrows. But at $500 out the door for a would be flagship headphone that was intended for listening at home or in a studio through a serious system... I don’t know.... I expected something more substantial.
 
The crux of this featherweight value is that in order to keep it properly seated on the listeners head, Sennheiser had to crank up the clamping force. Otherwise the light weight construction leaves it prone to moving too easily as it has little resistive value on its own. The clamping force is something that many have commented through the years as a supposed 'death grip'... Once again just like the HE400 won't snap my neck, the clamping force on the HD650 is not going to crush my skull. It is certainly wound a bit tighter than most, but I personally believing the clamping force has been measured perfectly to counteract the lightweight construction's tendency towards moving easily. It is a goldilocks value.... not too much, not too little... Just right. This is a nod to the design engineers.
 
Right off the bat my delusions of grandeur were dispelled. It is certainly nicer looking than its faux marble clad brother the 600 however as a supposed flagship headphone of such universal praise, I was underwhelmed by the look and build quality. Those who think this is immaterial are kidding themselves.... Aesthetics have value to the consuming public and audiophiles are most certainly not immune... The hifi world is littered with glitzy machined aluminum tone arms, satin metal surrounds for tweeters, anodized aluminum face plates with machine metal knobs, high gloss enamel finishes, lustrous wood side panels, frosted glass.. etc....etc...
 
The die-hard says that this is simply an indicator that they chose to pour all their cash into sound quality. OK maybe this is true.... lets see. 
 
Hook It Up! And Wait.
 
I did not want to be hasty with a plug and play attitude as I had heard that the out of the box, plug and play sound of the HD650 was disappointing (I heard this about 10 hours after I purchased it sadly) but that a 100 hours of burn in would get you a somewhat matured sounding headphone, so onto the vintage Realistic 64B it went. This older vintage rig is hooked up in a file cabinet at work and so can burn in a headphone out of site and outta mind while I still enjoy music on my main headphone rig…. A Violectric V100 tethered to a Laptop running JRiver via my Rega DAC with a Wyred 4 Sound uLink handling conversion duties to SPDIF. 
 
100 Hours - Impressions
 
After it had burned half the day on Thursday and all day Friday, Saturday and Sunday by the time I got in to work on Monday the 650 had clocked roughly 96 hours of burn in time. I plugged it into the Violectric V100 and listened to some newer redbook CD rips. Muse 2nd Law, Foo Fighters Wasting Light, and Gaslight Anthem The 59 Sound. 
 
The HD650 is not a bass head can. That is my first impression. Where the hell is this supposed ultimate bass weight?
 
A couple of local Head-Fiers down here in the Southland told me the 650 was really amp picky and that I would do better with a tube amp like a Woo WA6 or Bottlehead Crack. However my headphone amp is a Violectric amp which is what Sennheiser uses in their “Hall of Fame” set up and is one of Sennheiser’s Senior Project Manager Axel Grell's favorite amps for his own listening. A couple others mentioned changing the cable to a Cardas one, and one guy said I might need a different DAC to get the most out of it.
 
So in order to get the Sennheiser HD650 to sound good what I needed to do was:
 

1. Get a different amp
2. Get a different cable
3. Get a different DAC

​
Maybe I should get a different source, different interconnects, a new power conditioner and stop using CD's while I am at it eh? Mind you I do see where some could see this headphone as all they need and build out their entire system around it.... searching for another .5% of improvement with each piece of the puzzle... but I have already built my system(s) and am not really inclined to do a whole lot of kit rolling in order to optimize the synergy with this lone headphone when I have a half dozen others that sound fantastic through the rigs as is. 
 
So my immediate disappointment with the bass could’ve derailed this whole review. I was expecting Pro900 bass or Denon D5k bass without the 7khz ear razors or recessed mids... What I got was an all too polite rendition of EVERYTHING.
 
The low frequencies are extended, there is textural information galore, you can really hear the stick or the tom on the drum skins, the full decay of bass strings, mid range is sweet and smooth, and there is plenty, and I mean plenty, of high frequency detail and sonic information. Anyone who says the HD650 does not have enough treble energy or detail is, to these ears, not hearing straight.
 
But that ultimate bass weight, that Mike implicates all the time, it is not here IMHO.
 
The low frequency, midrange and treble are all recessed quite a bit. They do not hit you in the side of the head with impact. They don't even touch you. If this is what people are speaking of when they say the 650 is veiled then yes, it is veiled, but not in the sense that a certain portion of the frequency range is somewhat blurry or hidden.... Its more about air pressure that makes a headphone felt as well as heard. Open architecture does limit this but I've heard better open backs at giving you punch. 
 
I will hop on my soap box right here and say that one part of a headphone experience that is vital to me, is the overall weight of a headphones tone. I am not specifically talking about bass extension or articulation or even the bass frequencies in particular. What I am saying is that headphones with a tonal density to them…. A robust acoustic mass that move some air pressure to bring the music more to life…. That is critical for enjoying music in my book. Otherwise it sounds like music but doesn't feel like it.
 
It may not be critical for monitoring, mixing or mastering in a studio, or DJing or even for being an audiophile who wants to sample 24/192 and DSD audio tracks like they are a damn 10 year old Pinot Noir… but for the average Joe like myself who wants to simply strap on a set of headphones, cue up an album, hit play, sit back and enjoy some music…. The overall presentation doesn’t need to be “forward” but it needs to be felt as well as heard.
 
Oldies like Buddy Holly, Sam Cooke, and Bob Marley all have strong drums and bass rhythm that is presented most natural when the full weight of the instruments is presented... the kick drum and bass line at the opening of Dock of the Bay sets a strong foundation for Otis and the guitar to build off of. Alternative music like Smashing Pumpkins,  The Pixies, Jawbreaker, Dirtbombs, and Blur all have bass and drums that need punch. Punk rock and other guitar driven music like Social D, Operation Ivy, Van Halen, Bad Religion, The Ramones, Rancid, The Strokes, Vampire Weekend, Weezer, Gaslight Anthem.... they all have rhythm sections, and natural timbre that is presented best when it is presented with a fully developed full bodied sound.
 
Most people would rather listen to music through a great set of speakers because the music can be felt in your bones and people go to concerts because the live performance trumps every other experience. I saw Muse at Staples Center a month ago and the bass and drums absolutely rattled my bones.... Just vibrating you right down to your soul. And that is why 50,000 pack stadiums every night to see performances. Because the music overwhelms your senses. I saw the Ramones in Santa Barbara in the early 90's and it was the loudest show I've ever been to... Large Marshall double stack cabinets for both Dee Dee and Johnny and Marky's drums were mic... all in a small club (The Anaconda for anyone who cares) and the Ramones play tight so it was just a full on sonic assault.... transcendental to a young kid and still the best show I ever saw. 
 
To me, listening at home through a set of headphones should be a tamed extension of that experience. Obviously headphones can't give you what a live concert can... nor can they give you what well crafted speakers can, and speakers can't give you what amps and guitars and mic'd up drums can.... but each should have a measure of the other. The HD650, although tonally sweet and smooth and carrying some weight in its tone is similar but a bit more recessed than the Audeze LCD2, it just holds you too far back from the music FOR MY TASTE. It left me wanting for something more!
 
The HD650 often gets the compliment that "I could fall asleep with these on" and that to me sums up the HD650 perfectly.... It's kinda boring.
 
The HE400/ HD650 issue.
 
I’ve had a few people ask me which I prefer. The HE400 has a little more low end punch and the extra growl and mid range power makes it a better choice for my taste. Speaking strictly in audiophile terms the HD650 has the better acoustic chops. Its professionally damped driver fills out more evenly and more linearly but this linearity is still comes out anemic compared to the more live sounding Hifiman. . 
 
At lower listening levels the HE400 is a far better choice. It gives you a tad more flesh to sink your teeth into. A bit more punch in the low end and a live wire mid range that’s tipped up just enough to make rock music sound amazing. But as we travel up the volume ladder the Sennheiser becomes more stable and stout in its presentation, everything fills in evenly. The lows get stronger as the mids get sweeter etc... The HE400 although good to a point, can get crispy and its budget level planar membrane can start smearing tones and blurring separation on complex electronic fare where 100 or more different sounds are sometimes dubbed over the top of each other. The Senn is more resolving and surefooted through big sonic waves but like said, anemic... I could live with either, but if I could only have one, it’d be the 400. Even though it tends to get a little distorted when it is under powered and doesn't have that furthest reach of resolution. It's rock and roll presentation is more enjoyable.
 
Johnny Come Lately – The X1 P
 
Phillips open back X1 is priced a hundred short of the 650. But there are obvious similarities. Open back design, midrange price point. But one would assume that its beautiful aluminum cups, velvet ear pads, and leather headband come at a sonic price.
 
The X1 is a gorgeous looking headphone. Along with my D5000 and LCD2 it is one of my most sartorially minded. People like to contrast it against the Sennheiser Momentum…. No, the Momentum looks flimsy build and doesn’t hold a candle.
 
Next to the X1 the 650 looks very dated. The plastic finish is a glaring shortcoming up front for a headphone asking $200 more. The 650 is the technically superior headphone. For the same reasons the HE400 can't play this game the X1 can’t either… It doesn’t have that same surefootedness and linearity that the Sennheiser does, nor does it scale as well. But the X1 has a more rich and nourishing tone that will appeal to music lovers and bass heads alike. Its bass slams harder, it's musical vibe is just funner. It can also get a little crispy and sibilant in the upper register when volumes start creeping up whereas the 650 never breaks form. The Sennheiser is still the “better” headphone. But for a music lover like me I am not sure how important that is. Lately the X1 has been getting a ton of head time and that speaks to its engaging tone. It gives me that 'felt as well as heard' sound that I crave.
 
VS. My Favorites
 
Against both of my closed back favorites, the Sennheiser plays the same song. It is linear, well engineered, accurate and anemic. The Denon D5k and JVC DX700 are simply more dynamic more emotionally engaging, and immerse you in the music. They surround you in an envelope of tone.
 
The punch is there with both, but the JVC DX700 ups the ante by giving a sound stage worthy of an open back phone and providing not quite as linear but still fairly linear sound as things get louder and louder. I would choose the Denon and the JVC DX700 over the 650 every time. It simply doesn't give you as much of the song as they do. It is truncated in its presentation it sounds thin and lifeless compared to the two Japanese headphones. They are just too well rounded, dynamic and potent for the 650 (IMHO). They don't give anything away.  
 
Contrasting against the Japanese duo, the Sennheiser strikes me as the stuffy middle aged guy rocking a corporate polo, khakis and cheap patent leather shoes. He presents well enough in professional circles but doesn't really have the personality to charm. The 650 is the middle aged, mid level cog in the machine. The D5k and DX700 are sharp dressed 20 somethings from Tokyo with Italian cut suits and crepe sole oxfords. Their resume may not be as thick and they may not have the same number of professional accolades but they are dynamic, engaging and charismatic. They offer excitement and future glory that you will not find with the hum drum late 40's something sitting with his shoulders slouched in the lobby.
 
WRAP IT UP!
 
In closing the Sennheiser is by most normal youthful standards a little light in the ass. Some would call that a veil or laid back but it’s not laid back to me… That denotes a mellow, relaxing sound and a veil sounds like the treble is shelved down or certain parts are blurry. No this is about sound pressure levels. Air being moved by transducers. This is about 2 dimensional accuracy vs. 3 dimensional involvement. 
 
The caveat to that would be in a full size stereo rig.... In those scenarios the 650 sounds a lot better than most modern 32 ohm headphones.... The only 2 in my collection that best it on the integrated amp scene are my planar headphones... both of which have flat phase response and so don't do the poorly damped thing.... But in a typical dedicated headphone setting.... to me, the 650 is a bit boring. You are held back just a bit too far from the song to truly enjoy it. I dare say that the hype may be a bit overblown….. at the very least it does not line up very well with my taste. 
 
Mind you I didn't write this review to deride anyone who loves the HD650.... and I'm sure those of you that are fans of it will continue to enjoy it. But I do think there are a lot of people running around this site looking for answers, not wanting to spend their hard earned cash poorly.... and most people use this site to inform their future purchases. Because of some of the descriptive words I have heard people use, I think someone could get the wrong idea about the sound of the 650... when people call it dark, warm and full bodied.... I don't know that these words do the phones tone justice. At least not without building your entire system around the HD650. Contrasted against the greater landscape it is a bit light and lacking in body. Someone needs to say that. 
 
So I hope I do not get flamed but I think that someone out there deserves to get a little objectivity on this headphone rather than just more gushing about "greatest ever". No I am not a Beyer or AKG fan boy going subterfuge.. I am just an average consumer with average taste and listening habits trying to give others like me some reasonable perspective. 
 
I suppose if you dedicate all your resources to just this one headphone, you can make it sound spectacular.... But to the average head-fier who has the same low riding, subwoofin tendencies that I do. Who listens to Muse, Foo, the Black Keys, Gaslight Anthem, The Strokes.... modern music.... this may not be such a strong fit. 
 
Just saying.

When I first got my HD650s about 5 years ago, I have to be honest and say I wasn't thrilled. Listening to them over my DAC for the first time gave me a bad first impression. I purposely loaded my vinyl transfer of The Police's "Every Breath You Take" because it has a good balance of punch and snappy low, mid and high frequencies (again, I'm talking about my vinyl transfer, not the Remastered for CD version).
 
I was unimpressed by the lack of "WOW Factor" that I had heard from other users/reviewers. My DAC is a high-end Crane Song Avocet which has a very good solid state headphone amp built in. I then read about how these need a few hours of burn-in time, a concept that I wasn't sure was true, as other headphones I own have sounded the way they do out of the box; this was the first headphone purchase I made where burning in was a factor.
 
Skeptical about this phenomenon, I decided to run pink noise while at work for two weeks straight, without listening to music during the entire burning period. After the two week burn-in period, I listened to the same song again and this time there was a noticeable difference in how wide the stereo image sounded. The low frequencies sounded more extended, but I still felt the mids and highs (especially the high frequencies) were just not as present as I've heard them on some of my other cans (Grado SR80s, Sony V6s, AKG 240DF). The other headphones don't reproduce the low frequencies as good as the 650s, so for a while I wrote them off as having a general weakness in the mids/highs.
 
Over the next few months, I listened to all kinds of music with them and slowly began hearing about the "foam mod" and wondered if it would make a difference. I didn't want to risk damaging them, as the smaller foam disc inside each of the drivers doesn't seem like it can go back as it's sandwiched between two layers of plastic that cover each of the drivers. I decided to do this modification, because frankly, I wasn't listening to the 650s as much as I wanted to. After removing the small piece of foam from each of the drivers, I immediately noticed an improvement in the lows and mids; the lows had less "mud" and I was able to hear more detail in things like snare drums and hi hats. The next modification was the cable, and I decided to build one using the Cardas plugs, Canare Mini Star Quad and terminate it to a 1/8" Canare plug. Being able to remove the stock plug easily through the connectors gave me the ability to see if a cable upgrade really does make a difference, and it sure does! I gave up the flexibility of the stock cable, because the heavier cable is shorter and less friendly to moving around, but I noticed immediately that the sound stage improved a bit and I started being able to pick apart elements of the audio in ways I wasn't able to before.
 
The only thing I still wasn't satisfied about after the foam mod and cable upgrade was the high frequencies, until I listened to these through the Schiit Valhalla. I think the tubes on the Valhalla somehow have improved the upper frequencies on these headphones. When I listen to my Grado SR80s through the Valhalla, they almost sound too bright, so maybe the amp (and stock Schiit tubes) bump up the higher frequencies, it seems like it to me, and I think this bump works extremely well for the HD650s!
 
It took me a few years to find a combination that has transformed these into a beautiful listening experience; out of the box, they simply don't perform to their fullest potential (they definitely are picky when it comes to an amp, and I would try them on a valve amp as opposed to a SS amp for the full experience!) I bet many Tube amp enthusiasts are having a blast with these and rolling tubes! I'm honestly perfectly happy now with these and the Valhalla.

The HD 650s do just about everything right. Extremely forgiving yet detailed, it makes all music sound gorgeous. Absolutely dreamy, you'll find yourself lost within your music. Much of the sound attributes have been said before, e.g. the warmth and laid-back signature, so all I want to say is that if you ever had to buy a pair headphones solely for the enjoyment of music, pick the 650s. It's an absolute bargain at it's current price.

My only complaint is in aesthetics. If only it would look as beautiful and elegant as it sounds. Although, not really a complaint as the sound takes precedence and it's really not that ugly. Could use less plastic though.

I don't like this headphone. Or rather I don't enjoy this headphone. But I can't deny it's impressive.

Plagued with the typical Sennheiser problems of being built cheaply and being overpriced, yet it's really the only in its class, the audiophile's favorite.

That warm and dark sound, that you can never get tired of. That impedance curve that makes it scalable. This is the audiophile's dream, it may not be relevant today with all the FOTMs but it still remains a classic. Grab one used from the classifieds if you're into this kind of sound.

As someone who is into accuracy, it was natural that I prefer the HD600... the HD650 was too thick in the mid-bass and lower midrange and the highs was rolled off, but the roll off wasn't really bad as the clarity is there, but the veiled like sound comes from the mid-bass and lower midrange.

Some complain that it's slow, I disagree, it's pretty clean and fast, but not harsh. Technically impressive, very low distortion.

Recommended!

I have only had these headphones for a little over a month at the time of me writing this review. I choose to write the review now because I feel confident in my ability to properly asses these headphones from an objective point of view with minimal bias. This review was written at work over the course of a shift, it is by no means well layed out. 
 
First off....These headphones are understandably flat and dull when used without an amp, anyone expecting auditory greatness (Over the Ear) from a 3.5mm jack running off of your phone is insane. 
 
What I listened to on my HD650s: Classical, Rap, Rock, Classic Rock, Metal, Death Metal, Melodic Death Metal, Symphonic Death Metal, Alt Rock, Dubstep, Trance, Jazz, Techno, Pop, Progressive Rock, Progressive Metal. Television shows, Movies, PC games, Skype conversations. 
 
Quality of source material: Primarily 16-bit 44KHz ALAC, Vinyl, 24-bit 96KHz FLAC
 
What powered my HD650s: Tested on 2 amps at home in addition to my portable amp solution Fiio e17
 
Use: 6-8 Hours a day for a little over a month at home in chair/bed, walking, and even in my car.
 
Experience: Easily the best headphones I have ever owned. The bass response is superb and will lull your ears into nirvana. The highs are crisp and distinct but never feel like they are stabbing your ear canal. I decided to test MP3s with the HD650 and was astonished at how 320Kbps tracks were sounding through these cans. No where near perfect, but damned impressive for the source material. I listened to music the most sitting in my lazy boy chair at my computer or laying in bed. I have actually fallen asleep listening to these headphones, they are really comfortable. 
 
Conclusion: This review was kind of sloppy, but I can easily recommend these cans to anyone looking for a delicious audio experience. AMP MAKES ALL THE DIFFERENCE
 
 

I love my HD650 for rock, jazz and weightier orchestral pieces. The sound is very detailed but somehow dark (which is good with some recordings). This headphone never sounds obtrusive or hard. It is very comfortable. I have it as a companion to another great headphone, AKG k701, and they work great with their parts of my record collection.

These are a great pair of cans all around. Very few complaints. Fantastic value. I've been driving them with E17 / E09k - it may not be perfect but it sounds great to my ears!
 
These are the kind of headphones you forget you are wearing because they are so comfortable. The rolled off treble is great for long listening sessions.
 
I find that I tend to use them when I want my experience to be a little bit hands-off. The sound, the feel, etc. is all very comfortable. The bass is a little bit underwhelming, but it fits the 'comfortable' experience.  They are nonetheless quite detailed. They aren't bad at really low volumes, but I am more likely to reach for my grados if I want really low listening volume with clarity. 
 
The build quality is quite good. I am worried about the paint chipping though. 
 
They are a massive step up from entry level headphones and IMO about 75% of the way to hi-fi headphones (e.g. LCD3). 
 
In my opinion they work quite well with all genres of music, but are a little bit too laid back for rock. 

Thumbs up! 

Just got a pair of these for Christmas and have to say that I was very impressed with the box they came in, very solid packaging, and neatly organized cord. There is a 3.5mm adapter included in the box, something I was not used to coming from a pair of Grado SR225i cans.
The build quality is very good, I don't feel like I will scratch or dent them without a decently high tumble. The cord is detachable and feels like it will not likely give out anytime soon.
As for comfort, I never really found my old Grados that uncomfortable (I know you guys/gals on Head-fi and reviews on Amazon always talk about Grados being uncomfortable) but now I can hardly wear them after having used the HD 650s. It is a very comfortable fit once you get them adjusted nicely to your head.
As for sound quality, I play everything in FLAC or MP3 @ 320kps using Foobar2000 with the kernel streaming plugin.
Due to the fact I don't have my Maverick Audio TubeMagic D1 Plus Edition in yet, I have been trying to use the 3.5mm jack from my laptop to listen to music. The HD 650s don't sound very special through that source at all, they are very boring when plugged up to my android phone as well. I almost picked up my Grados again just until my amp came in, but I just like the feel of the HD 650s so much more.
I eventually used HDMI out from my laptop to my harman/kardon AV receiver along with Foobar2000 w/ WASAPI (manually selecting the receiver in the output list) and plugging my headphones into it as a source. This made the headphones sound much more worth their money and really blew me away.
Music I tested included Pink Floyd, The Beatles, Led Zeppelin, Daft Punk, OutKast, The Chemical Brothers, Kanye West, and Fleetwood Mac. I heard details in Time by Pink Floyd I have never noticed before.
I am very excited to get my Maverick Audio TubeMagic D1 Plus Edition in. My library is waiting for me to listen to everything over again.
If anyone wishes me to report in how the D1 sounds as a source for these cans let me know in the comments.

I'll try to be brief here, which is nearly impossible for me to do.
 
I bought this headphone last month and previously had two pairs. Those pairs had really anemic upper mids and had bloated mid-bass. This pair does not. I even used my old reference tracks I tried previously and this pair has a quite balanced sound signature. Not dead neutral or completely uncolored, but I would say it's just smooth sounding. Possibly one of the most musical headphones i've owned.
 
This headphone for me makes a lot of my crappy recordings that are harsh and fatiguing a bit easier on the ears. I don't ever get bombarded by treble or anything else. No shouty vocals or whatever else. It also doesn't make any very warm recordings worse by making them sound congested or less clear. I've found that they also seem to have better bass extension than my HD-600. Punch me if you want, but the bass on THIS HD-650 seems more controlled than that of my HD-600. It's closer to the bass quantity of my HD-580 (same driver I know).
 
Despite being very forgiving for bad recordings (only the garbage with the mids/treble cranked to max in the studio) it still need higher bitrate files. You can still tell the difference between high quality recordings and bad ones despite being both in FLAC.
 
These are very detailed. Nothing is missing, but all that detail is not shoved in my face. As hard as it is to believe, my DJ100 and HD-650 benefited more from my ODAC than the Q701. No idea why. The HD-650 seemed to become more revealing and detailed. The Q701..not as much.
 
This is a good headphone for when I just want to listen to my music and not be bothered by recording flaws. I can listen to these all day without fatigue.
 
The soundstage is better than that of the HD-600/598 IMO, but it's not larger. Better imaging etc. I think the ODAC is playing a role here too. Never thought such an improvement was possible unless my ears are playing tricks.
 
The sound is nice and full sounding, but not excessively warm. I thought I hated warm sounding headphones, but now I guess not.
 
This pair also doesn't seem to have sucked out upper mids, but at times there seems to be a very slight peak. Maybe a tiny one. I know this goes against what nearly everyone says. This pair also doesn't seem dark. The treble is very good and not lacking. It has slightly less than my DJ100.
 
Despite making my bad music sound a bit better than it should be, it still is quite accurate to how the recording is..sometimes. You often don't realize how bad the recordings are until you switch to a different headphones such as the KRKs, DJ100 or Q701.
 
I gave it a 1/5 for value. It's worth $400, but $500 is nuts! My $80 DJ100 with the same setup isn't that much worse and often even better in some areas. Both have some similarities. The DJ100 just has slightly more forward mids and more treble. DJ100 has better low bass. Sounds a little clearer too sometimes. Both are now my top 2 favorite headphones.
 
This review might be off the general consensus, but I don't care. This one is much more balanced than the others i've heard.
 
Setup was Headroom Micro Amp (not a portable amp an drives it with ease) from ODAC. I always use FLAC files. I previously used the Asgard with the HD-650, but found the Micro amp way better.
 
BTW this is as close to my DJ100's sound as I could find. My DJ100 sounds like a weird mix of an HD-650 and maybe a Sextett. Maybe the 650 and another AKG. The DJ100 is definitely a little more forward sounding, but still smooth sounding (with my setup, which I think is very neutral). I only mention this because I always wanted an open headphone that had some similarities to my DJ100.
 
NOTE: if this was priced at $350 retail it'd definitely get a 5/5 for value.
 
If you're curious I'd rank my Sennheisers as:
HD-650 > HD-580 | HD-598 > HD-600
 
Weird, I know..not a ton of difference between the 580 and 600. 580 just sounds better than the 600 to me. Clearer and with slightly more forward upper mids and maybe less bass.
 
Strange as it sounds, I tend to prefer the AKG type sound, but the HD-650 is just addicting.
 
EDIT: The only change after use I've noticed is that the lower mids smoothed out a bit. Out of the box they were a bit "shouty". Kind of like the PX100-II (for me) without an amp.
 
I also think it's a mistake to do many A/B comparisons of these headphones with something that's dramatically different (like a flat studio monitor). With crappy recordings the HD-650 will always sound better and it's easy to be fooled.
 
Oh yeah.. I also use these for gaming! 40 hours into Dark Souls and even use them for movies. The HD-650 can't match the soundstage of the Q701 though. HD-650 is obviously much warmer and a tiny bit bassier.

Very happy with them for the price and the sound is great i highly recommend the purchase if its your 1st set of quality head phones the music just doesn't come in it rolls in...
 
I will write a more detailed review once i get an amp to match them i have narrowed it down to the schiit lyr ,valhalla or maybe the bottlehead crack..who knows one things for sure its driving me mad trying to choose....
 
Peace :=)

I felt compelled to write about the performance of the HD 650 when used with upgraded cables. I purchased my HD 650s used from a Head-fier in Canada. They came with a nice burned-in Stefan Audio Arts (SAA) Equinox cable which I compared with the stock cable, and there was a very big improvement in performance. After using the Equinox cable for a long period, I recently upgraded to a  used SAA Endorphin cable which added increased performance I did not believe possible, especially in the area of bass authority, timbre naturalness, and soundstage renderings.
 
I also have tried and use the Cardas cable on my HD 600s which also adds noticeable improvements, although not as great as those generated by the SAA cables on the HD 650s.
 
I listen to vinyl on a VPI Aries with a Clearaudio MC, Nordost Tyr cables to a  phono stage in my Spectral preamp, then out to a WOO WA6 SE fed with Nordost Freys. I also use upgraded power cords and power conditioners as well as BDR carbon fiber isolation devices.
 
After listening to a bunch of cans at last weeks' CanJam at the RMAF in Denver, I am still impressed with the HD 650s and their performance vs price. I did listen to the new HD700s but not long enough to form a strong opinion, but they sounded better to me than the HD800s. THE AUDEZE LCD-2S WERE AMAZING with ALO cables into a Ray Samuels Dark Star!
 
In conclusion, if you really want to get the most out of the HD 650s (or the HD 600s), try some of the aftermarket cables available, if you can, on a demo basis.

This was my favorite headphone for some time. Mainly because its the first decent pair I owned.
However as I listened to other cans these became less and less important. Now all I see when I look at them is a plain headphone with dull sound.

Sennheiser HD650 review


Introduction
My HD650 was my first hi-fi headphone, and also one of my most priced possessions for well over a year. I regret nothing in buying these, but I plan on selling them since they do not get enough head time since I acquired my SR-202's. I only got these back yesterday, after sending them off to get the left driver repaired since it produced ringing in the sub-bass. This pair has the new drivers, in case you're interested.

I already wrote a detailed comparison between this headphone and the SR-202, but I felt that it was simply not a good review. As a result, I have decided to rewrite my review in a different fashion only focusing on one headphone at a time. Like my HD 25-1 II review, I meant to keep it concise and clear without leaving anything out. If you want extreme detail in the sound description, give my other review a read and tell me what you think.


Listening setup
I have used these headphones with many an amplifier, including but not limited to the AMB Mini3, Audio-GD NFB-12 and Little Dot MK IV. For this review I used my HD650 out of the headphone output of the NFB-12.

I personally have not heard any significant difference between different amps, but I do believe that differences may exist.


Pictures






Build quality
The paint on the headband has the tendency to chip off. This is visible in the 6th image above. It's not really noticeable under normal use, but still unacceptable for this kind of equipment imo. I have not heard of a good method of preventing the paint from chipping, since it happened to even those who were extremely careful with it.

Other than this small issue, I would say these are incredibly well built and feel like they could easily withstand 20 years of regular use. They also look absolutely stunning, in my opinion.


Cable & accessories
The cable is really well built, and is detachable too. It feels smooth, strong, and will not curl up in any way. I see no reason to get aftermarket cables with this headphone, despite the large popularity of such cables.

The headphone comes with a 6.3mm -> 3.5mm adapter cable of similar high quality.
It also comes with a travel box, which although not of super high build quality, does its job quite well. On one of the corners the cardboard started tearing (see picture 7), and I have no idea how this happened.


Comfort & isolation
These headphones are amazing in terms of comfort. It's the most comfortable headphone I have tried to date, which is no easy feat. In my case, the clamping force is of medium strength, although people have reported it to be too high and found that slightly bending the black metal ribbon fixed the issue.
The cups can be adjusted in height, and the entire construction can be twisted. This ensures that it will fit pretty much all heads comfortably.
The pads are made out of velour, and are very soft. They do wear after some time, and people have reported that washing or replacing them for new ones has increased comfort and sound quality.

These headphones are of open design, but still have a decent amount of isolation. Not enough to serve for portable use by a long shot, but more than enough to make you want to put them off when having a conversation. The sound leakage is also reduced because of this isolation, and as long as you don't listen to your music loudly the sound leakage is too soft to bother a person sitting next to you in a normal office environment.


Sound quality
I find the HD650's very good sounding, and definitely worth their price in this regard. Even with the price increases of about a year ago. I got these sound impressions completely based of my other review of the HD650, as well as my own memory.

Frequency response This can is not flat. It has a considerable mid-bass boost and an overall warm sound. They sound very laid-back and smooth with most music. The treble is fairly flat, although a bit attenuated. They are relatively neutral, and can become next to completely flat with slight EQ. Personally I like their natural sound signature since it's fun.

Bass The bass extension is nice and deep. They have a good amount of bass thump and is excellent for electronic genres in my opinion. They are good with rumbling bass guitars and convey a strong sense of energy.

Mids The mids are sometimes drowned out a bit by the bass, but overall it feels pretty flat. The mids especially feel nice and smooth and present a good natural timbre. Instruments like acoustic guitars sound very good on the HD650 because of its smooth nature.

Treble Treble feels fairly flat, but attenuated compared to mids and bass. Cymbals sound good, and there is no sibilance. There is no harshness and they do not sound fatiguing. The treble does lack a bit of detail, but is otherwise of excellent quality.

Soundstage Every headphone has a weakest link, and for the HD650 it's its soundstage. It conveys a good sense of width and distance, though it's smaller than my electrostatic SR-202. The soundstage is smoothened out a lot, and has relatively bad instrument separation. In cases where many instruments are present, it feels like the can loses control and puts it in one big blob of sound. Overall it's not bad, but it leaves me wanting for more.


Conclusion
Apart from their relatively weak soundstage, these are very good sounding headphones. Taking into consideration their excellent build quality and comfort, I can see why these are so popular. While my experience with other mid-fi cans is limited, this one definitely has my glowing recommendation at its price point. Especially when comparing it to it's price before they raised it.