Sennheiser HD 650 Headphones

There is not much to say. Only making this review to help indecided people, and contribute to the forum as a member who was helped too.
Bought this can second hand for 225 Eur. Practicly new and great price for what it is, i must say.
I'm no audio engineer, so i will keep things simple. Not a native english speaker, so my english may have some mistakes. It's my first review.
Hope you enjoy. 
 
My history: 
 
Started not long ago. I was a former basshead, until i discovered the older momentum and open backs. Till then i bought average gear, some i found disapointing. 
My best basshead cans are the Sony XBA-H3, but i get full of sticking things in my ear. So i started searching and found this forum.
Which led me to the momentum as i refered, fidelio x2 and hd650. Amps i'm using fiio e12 and ifi idsd micro.
 
 
Sound Caracteristics:
 
Bass: It's well defined, extends well and has quite impact. Cool dry bass and transparent. A tad bit subass would better, but i think i still will find a solution for it.
 
Mids: Great midrange, nice vocals, not much to say.
 
Treble: Not veiled, very detailed and effortless. Not fatiguing. Extended.
 
Soundstage: Quite big, bigger then on the Fidelio X2 IMO, which is claimed to have a big soundstage comparable to dt880 and dt990 or even better.
 
 
 
And now about the myths.
 
Myths:
 
 
Veiled -
 
Probably one of the biggest myths sorrounding this cans, defenitly to disagree in my experience. Might be true for the older version, but not this one.
For me they have better highs then momentum, nad 50, fidelio x2, sonys current lines as far i noticed. And they never complain about veiled sound on those.
The 650 might have one of the best highs around, well detailed and musical. Not easy to achieve. Create bright phones is easier, like boosting bass freq.
Its a unique phone with unique highs. They say they sound dark. If it is, its in a cool way.
PS: I'm in my twienties, i dont need that much treble, but you dont lose that much treble sensetivity with age... 
 
 
Loads of power-
 
When i started  to read this forum, the amp i thought i needed for HD650:
 
 
 
What i actually needed:
 
  
 
 
The reason why i bought the iidsd micro, which has an 4000mW headamp. 3 main gain. The ifi audio engineers sad to use the lowest one: Eco mode (>250 mW @ 16 Ohm). 
I was convinced at least i needed normal or turbo mode (5.5V/1,900 mW @ 16 Ohm to 10.0V/4,000 mW @ 16 Ohm)
Guess what!? The first one had the best sound. Lossy and lossless. I had to put it around 3o clock for ideal performance (acording to ifi too) It's not about power but to find the sweet spot. 
 
Original cable somehow creates a botleneck to the sound -
 
Some tried to get the veil disapear with other cables like the senns cable was the fault. I still use the originall cable, and get a clear defined sound.
It would be nonsense and desrespect to its clients if that would be the case. We are talking about a 13 years sucessfull HP here. It would be wierd. 

 
Bloated/Undefined Bass - 
 
Doesnt seem to be true either, it doesnt bleed anywhere. The only thing needed is a bit more subass.
 
Speed-
 
Since the bass is defined it seems fast enough for all genres. And i m using extra bass function of the idsd.
 
Small Soundstage-
 
Some say big, some say a bit claustrofobic... Well i say big andd not surprisingly, because it has good treble. Sometimes it feels more speaker like. Not saying its like a HD800, but its big and envolving.
When i was amping them at norma/turbo mode it didnt was that big. So again don't overamp.
 
Not suited for fun genres, it makes you sleep-
 
I'm a big fan of electronic and rytmic genres, and the HD650 goes very well for those. Dark sound gives sometimes an undergound feeling to some electronic tracks.
Will make a list of test tracks, and make an evaluation from 1-10 for the permance of the HD650 on those tracks:
 
Nu Disco:
 
-9.5   -9
-9.5 -10
Great midrange which is needed in this tracks.
 
House:
 
-9.5-9
Great bass impact, just a bit subass needed... Speed ok. Its more about groove.
 
UK Garage House/ Future Bass:
 
-7.5 -8.5
-5.5 This is a dificult genre, lots of subass... failed the last emotion.
But the rest ok, great underground dark urban sound feelings.
 
Progressive House:
 
-9.5-10
-10-9
Senn delivers here, this tipe of genre you need impact bass, rythm and stage. Delivers all three.
 
Funky House/ Funk House (Lots of groove & vocals):

-9.5-10
-9 -10
This genre has speed, vocals, rythm, highs and its ok for HD650.
 
Classic House/ Acid House:
 
-9 -10
-10-9
Looks they made it for this genre, great underground feeling due its darker sound, but great soundstage, transparent bass, great vocals.

Tech House:
 
-10-10
Perfect! No lack speed! Great club sound! How can you fall asleep !?xD
 
Deep House:
 
-9.5-10
-10-10
-8  Deep House is that genre you listen you in bars and some mistake it
with "elevator music"...  . Its slow 90bpm, but needs atmosfere, and 650 delivers it. Enough bass, no veil.

Chill Wave:
 
-9.5-10
-9 -9
-10 -10
 
This genre has a lot of highs. No problem for the no veiled 650 IMO. Great detail.
 
Electro House: (They call it EDM to):
 
-9  -10
-10 -9


This is not a easy genre, quite some speed, lots of changes of rythm, big stage but its enganging for me.

Trance 90s,00s:

-8 -8
-8 -9
Sounds ok for me in trance.
 
Trap:
-10 -9.5
Delivers well in one of the more dificult genres. A bit subass laking mabie.

Instrumental ​Hip Hop:
-10-10


And there is much more...
Dont listen much Dubstep or DnB so i cant pronounce about it.
About other genres i think its alot been talked around about the performance of 650s.

Hope you enjoyed reading or listening.

At the end i'm only doing this because:
 
   
 
 
-

EDIT: 7/7/16
 
I am redoing this review I posted in 2015 because it was too short. For this review of the HD650, I will be going into much more detail about the sound, pros and cons, certain tracks that make these headphones shine, and how DSP plugins can make this headphone (or pretty much any headphone) come alive.
 
First, let's go over the build quality and comfort.
 
The HD650s are completely plastic on the outside, except for the metal grills and metal adjustment band. For the 2 years I have had them so far, there have been no paint chips or places where the paint has rubbed off from use. Keep in mind, I have taken extremely good care of them, and made sure to never place them on hard or rough surfaces. If you do that you will find the paint will come off eventually as others have said in their reviews. I really like the gray color all around, and personally like it better than the HD600 and HD580 design and color.
 
These are the second most comfortable headphones I have owned, right behind the Beyerdynamic DT800/T1. The clamping force is tight at first, but over time it loses that tightness and stays comfortable. I have a narrower and taller head than many, so I need to click the headband adjustment down 9 clicks in order for it to fit over my ears. These also weigh very little, and there have been times where I've worn them for 4+ hours and forgot they were on my head. I used the original pads for about a year before I replaced them, and then recently replaced them again a few month ago, but they have compressed quicker than the other 2 pads for some reason. I suggest before you buy replacement pads for these, make sure they aren't fake and are from an authorized Sennheiser seller or from Sennheiser themselves, because I may have gotten fake ones since they got flat in less than 5 months. Flat and compressed pads really affect the sound negatively and caused my pair to have more bass in one cup than the other.
 
For reference, I am using the JDS Labs ODAC with the Objective 2 amp. Yeah, many people on this site will criticize me for using such a “lowly” source and amp, but they sound good and are neutral and flat, as they should be. The O2 powers my HD650 very well. Also, I do not believe in cables making a difference in sound, so I am using the stock cable, which is plenty durable enough for years of use. Let's just say I'm a bit objective when it comes to audio tech.
 
 
If I were to describe the HD650s sound in one word, it would be natural. Very natural, smooth, and non-fatiguing. I remember first listening to these, and saying to myself, "FINALLY! A headphone I can LISTEN to!" These have no exaggerated lows, mids, or highs. I keep telling people that these remind me very much of high quality speakers. In general I like the way speakers portray music more than headphones, but I am starting to rethink that as the HD650s immerse you even more than speakers in my opinion.
 
Starting with the lows, these have a somewhat relaxed bass tone. The sub bass is definitely there, but is not emphasized, and may be very slightly rolled off. Compared to planar magnetics, these lose the sub bass battle, but I am ok with that. I have experimented with EQ in the 25-50 Hz range, and found if I raise this area by about 4 decibels, the sub bass is more present and not distorted at all. The mid bass and low mids are raised ever so slightly, giving the headphones that lush and warm feel I love so much. Yet, it does not affect the rest of the frequencies, and makes recordings with little information in this range sound smoother and and less analytical.
 
The mids are where this headphone beats pretty much every headphone I have tried ever. The mids are incredibly realistic and natural, and makes instruments sound like the instrument they are supposed to be. Compared to other headphones such as the Hifiman HE-400i, Beyerdynamic DT800, and even the T1, the mids outclass them all because of how natural they sound. I feel with those other headphones, the mids are overshadowed by the higher treble response giving the impression of the mids being sucked out. They have more of a V and U shape response as opposed to the HD650s flatter response. Yes, many will say the mids in the HD650s are emphasized and too lush, but the very reason I have fallen in love with their sound signature is because of the smooth mids and treble. Many headphones just sound too analytical and sharp in the mid to treble region. Not so with the HD650s.
 
Speaking of treble, these have probably the smoothest treble I have heard from any sound reproduction device, speakers included. There are no peaks in the treble, and that is why these sound so smooth. These are never fatiguing, and are perfectly suitable for even the worst recordings (examples of which I will add to the music section). And with that note, there is something very important I need to address about the HD650s: the dreaded “veil”. Simply put, these have no “veil” and I don't understand why people keep saying they do. The high frequencies are present, and do NOT roll off. The treble extends all the way to 20 Khz, and frequency graphs support this. Perhaps before these headphones got revised in 2007, they had some sort of veil. But this new version has just as much extension as the HD600. So, these have plenty of treble detail and extension, just enough for me to not get fatiguing. Sure, compared to the T1 and Hifiman HE-400i these have less treble quantity, but the quality is exactly the same in my opinion. Even if the treble is less present than many headphones, I find it strikes a perfect balance between natural and realistic.
 
 
Now, I will list a number of music examples that I find bring out the HD650s strengths, and maybe a few of it's weaknesses:
 
 
 

 
 
This is a very well recorded piece of classical music, a genre I find the HD650 to excel at. In the beginning and in the middle of the piece there is a timpani on the right side and with the right headphones, sounds incredibly realistic. The HD650s make me sometimes believe that the players are in the same room! Just goes to show that with well recorded music, headphones sound their best.
 
 

 
No doubt everyone has heard this electronic piece from the 80s. This is one of the better recorded versions, and really shines with headphones with extended bass. The HD650 doesn't do as well in the sub bass as say planar magnetics, but I find them to be at a realistic level of what the mastering room would have heard the recording. If I want a little more bass, I just EQ the 25-50 hz range up a few decibels. Also, there are subtle treble details in this composition that the HD650s bring out beautifully.
 

 
Bet you saw this one coming, an extremely popular song that sounds incredibly good on good headphones. In particular the vocals are without sibilance and the drums are at the perfect level. The HD650s bring so much out of this recording, including the detail in the drums. Why can't music be mastered like this anymore?
 
 

 
I put this one on here because it is a harsher recording. The solo vocals were obviously recorded with a lot of compression and sounds like someone turned the treble all the way up on their big chunky 80s equalizer. On the Hifiman HE-400i and Beyer DT880, this song is almost unbearable. But, the HD650 tones down the harshness just enough, but still is revealing of the harshness.
 
 

 
Yes… I know… It's a Backstreet Boys song, but bear with me here. I chose this song solely for the only reason to show how the HD650 makes harsh recordings sound better. This one, in my opinion, is even harsher than Broken Wings. At the 0:48 mark, there are cymbals and really harsh vocals that have a lot of presence. I've listened to this on the AKG K712s, and it is downright PAINFUL. Thankfully, the HD650s save the day once again, and turn down the harshness just enough without sacrificing detail.
 
 
 

 
This is an incredibly beautiful rendition of Pachelbel's Canon in D. And, it is spectacularly recorded too. With the HD650, it's easy to get lost in the sea of the ambiance this piece has. The slight mid bass bloom the HD650s have make this piece incredibly immersive and lush. And everything sounds very realistic, especially the strings and plucked instruments. 
 
 
 

 
This is extremely impressive on any headphone, but especially the HD650s. The cello on the left at the beginning is so darn realistic because of the binaural recording that Dr. Chesky did. Really, you can't go wrong with any of the binaural tracks that Dr. Chesky has made, because they are meant for headphones and make you feel like you are really there.
By the way, I didn't purposely pick videos that have the same music album info layout, those were just the best quality I could find on Youtube.
 
 
 
Next, I want to talk about how you can squeeze every ounce of sound quality out of the HD650s: Digital Signal Processing.
 
Many people are very much against DSP plugins, but if you use them the right way, it can be a transforming experience.
 
There is a software plugin called Sonarworks Reference 3. Used mostly by recording engineers and music producers, this plugin takes your headphones or speakers and calibrates their frequency response to be reference monitor flat. Basically, the program equalizes the response of your set of headphones, and makes them suitable for mixing and mastering in a studio.
 
 

 
 
 
As you can see here, the program takes the average frequency response of the HD650 and corrects any deviations from whatever curve you select, whether it be flat, B&K curve, or your own custom curve. The blue line shows the average response of the HD650s, and the green line is the correction curve. It claims to have an accuracy of +- 3 db across the whole range, and it certainly sounds like it to me. They also have an option to send in your headphones to be measured and calibrated, having an accuracy of +- 1 db. This is a very good option for those who want the convenience of headphones, but have the sound of accurate studio monitors. Or, like me, someone who want the most accurate sound possible. I have also tested the AKG K240 Studio with this software, and to my surprise they sound strikingly similar to the HD650 when calibrated, at a significantly lower cost. The correction curve makes the HD650 have great sub-bass response, less mid bass bloom, and even smoother more present treble. Even with the default calibration, this program makes the HD650s sound like speakers, and that is what I've always wanted in headphones.
 
 
 

 
 
The fun doesn't stop there! I have been using the ToneBoosters Isone VST plugin for about a year, and it wasn't until I used it with Sonarworks that I was blown away by it. Essentially, this plugin gives you the option to emulate a 2 channel studio environment, complete with room size, reflections, and even an anechoic chamber. I use this plugin mostly for it's crossfeed settings, but with the addition of the Sonarworks software, the results are shockingly convincing. After adjusting the HRTF to meet what I find my head and ear size to be, I could swear there are speakers in front of me producing the sound. This is what I imagine a poor man's Smyth Realiser would be. In fact, I would go so far as to say it sounds better than a really good 2 channel speaker system, because you have a controlled simulated environment without any room imperfections or resonances. Technology has really come a long way with these plugins, and I wouldn't be surprised if 3D audio became a mainstream thing in the years to come.
 
Comparisons:
 
Vs. HD580
I bought the HD580 2 years ago before I had the HD650, but I remember the sound well enough to describe the comparisons between the two. The HD580 did not have enough bass for me, and they seemed to roll off to my ears in the upper treble. The HD650 is more extended at both ends, is warmer, but has pretty much the same midrange. Since the HD580 and HD600 are similar but the 600 is an upgrade, I would assume the HD600 has just as much extension as the 650.
 
Vs. Hifiman HE-400i
These headphones were amazing when I tried them. I was floored by their flat extended bass all the way down to 20 hz. In the end I returned them because they were too analytical sounding for me. There was enough bass, but the midrange was overshadowed by the treble peaks and made things sound unnatural in the end. However, these do have better treble detail than the HD650, but it is directly a result of higher treble response, not of treble quality. In fact, I have experimented with EQ to raise the HD650s treble higher, and got a very similar result of higher treble detail. So, these beat the HD650 in sub-bass only for me. Also, I would say the HD650s have better soundstage than the 400i.
 
Vs. Beyerdynamic DT880 + T1
It's been a while since I have had these two headphones, because I have sold pretty much everything since I started using the 650s. Both Beyerdynamics have great treble detail and clear crisp sound. However, I did not like either for long listening sessions, because of the painful treble peaks Beyers are known for. Compared to the 650, both Beyers have less lush mids, more treble, and about the same bass, but both are more extended. These both are on the list of the Sonarworks software, and I have yet to try them with it, as I am sure the software will tame the peak very well.
 
Vs. AKG K712+K612
Again, it's been a while, but I remember the AKGs excelling in soundstage only. The K712s had slightly more extended bass, but lots of mid and treble peaks that made things sound weird. The K612 had less peaks, but the midrange was a bit unnatural and analytical. Again, the K712 is on the Sonarworks plugin list, so these can be corrected to sound flat and probably maintain that better soundstage.
 
 
Final thoughts:
 
 
I have gone through at least a dozen headphones in the past 3 or so years I got into the hobby. I have since sold pretty much all of the ones above $200, except for the HD650. That should tell you how good they are, that they even outclass the flagship Beyerdynamic T1 in my opinion, at least when it comes to natural and realistic sound signature. I have yet to try the HD800, but if I were to make a prediction, I probably will still like the HD650 better. If you are into lots of treble detail, these will probably not be for you. But, if you like a smooth sound without peaks across the whole frequency range, these should be on your list to try. Thanks for reading!
 
 
 
 
 
 
 
 
 

I can't imagine another 650 review is needed for the known universe, especially here on headfi. While I enjoy reading them, I also don't take the "objective" reviews seriously. While I would everyone to have the cans that move them into a space for deep listening for music, I can only be concerned here with my ears. And what I hear from the 650 goes beyond the "veil" or analytical accounts of treble range or sub bass. What we have here is an artistic expression - masterfully done. It's more than just the science or looks. What I know is that from the very first point I put these on, I feel myself falling deeply into the music, even my songs produced poorly or poorly ripped or just plain old. I entered into the zone of music for some profound enjoyment of different musical artists.
 
In listening, the number one factor for enjoying music still comes down to me, the state of my mind, my ability to listen deeply. All I ask of the cans is to meet me there when I'm ready.
 
When I'm open and wearing these headphones, I fully music.
 
With these cans, music is a verb.

Everything sounds great, extremely clean and extremely detailed on the HD 650.
 
Fantastic clean sound, fantastic resolution, fantastic tone, warm, extremely well balanced, great bass (not boosted), very detailed sound, well separated instruments, very present sound, great sound stage, the highs and mids are smooth, clean and sound very musically.
 
And how about the infamous veil of the HD 650? It, definitely, does not exist. Perhaps on the old models, with the black drive, it could be true. On my new model, with the silver drive, there is absolutely no veil.

Everything sounds great, extremely clean and extremely detailed on the HD 650.
 
Fantastic clean sound, fantastic resolution, fantastic tone, warm, extremely well balanced, great bass (not boosted), very detailed sound, well separated instruments, very present sound, great sound stage, the highs and mids are smooth, clean and sound very musically.
 
And how about the infamous veil of the HD 650? It, definitely, does not exist. Perhaps on the old models, with the black drive, it could be true. On my new model, with the silver drive, there is absolutely no veil.

These headphones are superb in their presentation of rich, harmonic tones. They are not in your face headphones... the bass doesn't have the visceral impact of other headphones, and the highs are not cutting or piercing in any way. These headphones are smooth in a way that other headphones just can't match... they flesh out the tonality of the music, and present it as if you were sitting in the tenth row. You're left to close your eyes and take it all in, without it being pushed at you the way newer, more exciting headphones may do.
 
The midrange can be lush, organic and supremely holographic with the right gear. The bass is controlled, slightly emphasized compared to completely flat headphones, but in my opinion, there is just enough emphasis to keep things sounding balanced. I'm not left focusing on the impact of the bass, or the sparkle of the treble. There is some of that, but the real star of the show is the smooth, romantic tone. Guitar and vocals really shine for me with the 650's, in a way that is just so natural and smooth. The long listening sessions without any kind of fatigue make these headphones a true classic.
 
If you're looking to drive these headphones to their full potential, I would recommend a good OTL amp. The Bottlehead Crack, Woo WA2, or the LaFigaro 339 are probably the three that really bring out the best in these headphones. If you're looking for a cheaper solution, go for a DAC/amp combo that uses a tube... the Aune T1, or the Project Ember. Without one of these, you'll most likely find the 650's to sound somewhat unexciting, especially if you compare them with newer headphones. This is usually why a lot of people end up selling these headphones, moving on to better gear, and then buying them back. You've been warned! For the low price they're selling at now, they are well worth keeping and enjoying.

I bought the HD650 after owning a number of equally good headphones, including the Beyerdynamic DT880 Pro, DT990 Pro, AKG K702 65th Anniversary, and AKG K612 Pro. I'd have to say that while the HD650 has many competitors nowadays that it didn't have when it debuted in 2003; especially lower than its MSRP of USD 500, it nonetheless holds its own and still offers qualities that many of them do not offer. 
 
The HD650 is the most recent incarnation of its family of headphones. The basic driver design and headband design as far as I can tell dates back to the late 1980s-early 1990s with the HD545 and HD565. The design takes inspiration from Sennheiser's volume production version of their 16,000 (1991 money) dollar Orpheus HE-90 electrostatic flagship, the HE-60 "Baby Orpheus". In around 1993 Sennheiser launched the HD580 "Precision", in 1995, they launched the HD580 Jubilee Edition to celebrate their 50 year history. It had metal earcup grills instead of plastic ones, McLaren F1-esque carbon fiber furniture, and was sonically identical to the HD600, which was launched the following year in 1996. The HD600 had blueish granite furniture, and a sound comparatively warm and lush for its time while retaining a good level of neutrality. Then in 2003 came the HD650, retaining its position of Sennheiser's flagship headphone until the launch of the technical masterpiece, the HD800. The HD650 and HD600 are still sold together, with retail prices of 500 dollars and 400 dollars, respectively. While the HD600 earned itself the reputation of being the "Veiled Senn" due to its relatively warmer and more relaxed treble compared to similar flagships such as the Beyerdynamic DT990 and AKG K501, the HD650 has arguably been more deserving of the title. The HD650 was known by detractors for having a veiled, dark treble, a compressed soundstage, and a boosted, almost obese sounding mid bass; while the HD600 was the neutral of the two. However in 2010, Sennheiser retuned and updated the drivers on the HD650 to give it a less thick and a more energetic sound. The bass was lowered, the treble was raised, and the soundstage opened a bit more as a result. 2010 updated HD650s can be identified by their silver diaphragm shields, vs the black shields of the 2003 models. My HD650s are a 2014 model with the silver shields, and mine comes in a black black box and updated slip box, whereas the 2003-2013 pre and post retuning HD650s had a silver box and corrugated outer packaging slip box design. According to some unconfirmed rumors, the HD650 was retuned a second time to sound even more neutral for the 2014 model. I previously owned a 2010 HD650 with a silver box, and while there might have been more darkness and a bit more bass in that previous model, I can neither confirm nor deny this, as it may be a placebo or anecdote.
 
Here are some pictures of the 650's family members. The images belong to their respective owners. Just click on the names of the headphones. 
 
HE-60 "Baby Orpheus"
 
HD565 "Ovation" 
 
HD580 "Precision" 
 
HD580 Jubilee
 
HD600 
 
HD650 (black driver)
 
HD650 (silver driver)
 
Build-wise, the HD650 is a timeless and no-frills modular design of mostly plastic and some metal. The outside headband, the bales and the ear cups are plastic, while the inner headband is spring steel and the outside earcup grill is some sort of metal mesh. The headphone can be disassembled by hand to its component parts and basically every part can be purchased from Sennheiser and replaced. That's something you don't see on many headphones today. The dual sided cable is detachable and has two pins for each side, making the headphone easy to run balanced. Just unplug the included cable and plug a balanced one in. The stock cable has decent enough shielding, is dual channeled, is about 10 feet long, and terminates to a 6.35 mm stereo plug with an excellent 6.35 to 3.5 mm adaptor cable that will not put strain on the 3.5 mm output jack of your source device. The cable doesn't tangle easily and doesn't retain kinks. I would have liked the y-splitter to have been a bit lower but that is all I have to complain about. I have not used a Venus Audio or Cardas Canare cable on the HD650, so I can neither confirm nor deny whether they are worth the purchase. My biggest complaint is that replacement ear pads are 60 dollars from Sennheiser, making them very expensive considering they have a tendency to flatten out after a couple of years. There are third party Chinese made ones on eBay for half the price though. 
 
Comfort-wise, I didn't originally like the HD650. I found the spring steel headband, while extremely durable, made it a vice grip on my head, causing a headache. Another side effect of this clamp was that the pressure caused the velour ear pads to prematurely collapse, leading to my ears pressing against the foam driver disks, making them red hot and sore. I find that the HD650 doesn't have deep enough ear pads, and the arey fairly narrow, causing the edges of the pads to rest on the backs of my ears. I found that stretching the headband out (by taking the ear pads off and placing the HD650 over a speaker cabinet overnight) lessened the clamp, and rotating the cup pivots to put more clamp on my temples made the ear pads keep their shape, and now my ears are no longer pressing against the drivers. I find this to be a lot of fiddle work just to make a headphone comfortable enough. Removing the foam driver covers does give a little more depth, though it makes the sound a little brighter. This might be desirable for some people though.
 
Personally I would have liked Sennheiser to have stuffed the HD650 ear pads with a denser material like gel or double memory foam to keep the shape for longer periods of time.
 
The hand band is a nylon-type material and has plenty of padding. There is an indentation in the middle of the pad so you can rest the headphone on a stand and not dent the padding, and for people with a Sagittal rest in the middle of their heads, this can provide a little more comfort as the headband isn't hanging up on the ridge and causing aches from hot spots.  
 
As amplification goes, the Sennheiser HD650 is a headphone like prefers a powerful yet somewhat lush sounding amplifier or tubes on an amplifier. Though it is 300 ohms, the HD650 is quite a sensitive headphone, which means one will not have to crank up the gain on an amplifier to get a satisfying listening level, and will not hear as much amplifier strain. I was able to listen to the HD650 at perfectly satisfying listening levels from the headphone jack on my iPhone 5, and it also sounded good on the FiiO E07K portable amp and DAC I owned. The HD650 is more performance hungry than gain hungry. The better the amp to feed it power, the better it will sound. The HD650 isn't as system-picky as AKG headphones like the K702 or K712 Pro, so it is easier to attain a better sounding synergy with. The HD650 DOES prefer an amp that has a powerful sound to it, so solid state or hybrid amps are more preferable. All-tube amps such as the Woo Audio WA6, WA7 Fireflies and WA6-SE are supposed to sound excellent with the HD650 due to their transparency and power while still being refined. Higher end solid state amps such as the Violectric HPA-V200, Burson Audio Soloist and Conductor, and Meridian Audio Prime are also said to be great with the HD650.
 
I personally use my Schiit Audio Lyr 2, which is a powerful sounding yet thick and refined hybrid headphone amplifier with the HD650s. It still doesn't make them bass cannons or treble monsters, as the HD650 will tend to keep its softer sound regardless, but on low gain it has plenty of power and refinement. On high gain, however, the Lyr 2 becomes a bit too gain happy and aggressive with its stock tubes on the HD650, making the midrange and lower treble too forward and splashy sounding. Low gain is the better setting and is more controlled sounding with the gain-sensitive HD650s.
 
Now for sound: 
 
The HD650 was and still remains unique, as unlike most Germanic headphones, and more similar to Japanese headphones, its sound is definitely tuned by the ear. And what I mean by this is that rather than being tuned to dig from the lowest to highest frequency, HD650's sound is slightly n-shaped with an intimate midrange, a polite treble and warm bass. 
 
Treble-wise, the HD650 has very good extension with some elevation in the very top end. I don't consider it to have rolled off treble like newer Sony headphones have, though it's not a highly dynamic and front stage treble like on some Beyerdynamic headphones. It's present, yet subtle. The lack of a ton of lower to mid treble DOES make the HD650 a little less than perfect for orchestral music due to less  airiness, but it still has enough texture for acoustic music. That said, the HD650 will still show sibilances and some grain with poorly recorded music. Extremely sibilant tracks, especially on lower powered systems that may strain somewhat, will still have some harshness, even on the HD650, and the slight graininess to the lower treble can add to this. But it's infrequent enough that I don't consider this to be a deal breaker in any way.
 
Mids are the true forté for the HD650. The mids are fairly intimate and forward from the lower midrange to the upper midrange. After listening to the HD650s, many other headphones will often sound "hollow" or "scooped", with some withdrawal or midrange recession in comparison. Female and male singers alike sound equally strong, and instruments have a natural timbre to them. People who love a front and center midrange without the added brightness of the treble will love the HD650. There is little to fault. As I mentioned in the amplification section, though, watch out for amplifiers that are overly forward sounding, as they can make the mid-forward HD650 harsh, brash or blarey. Headphone amplifiers and tubes with a neutral to somewhat soft midrange work best with the HD650. 
 
Bass is an interesting point for the HD650s=, and along with treble, is responsible for the HD650's highly enjoyable midrange. Upper to mid bass notes are forward, textured and extremely present on the HD650. It does not have that overly "groovy" sounding bass like the AKG K240 MKII/Studio due to a highly boosted upper bass, but its bass is more upper and mid-focused than say, a Beyerdynamic DT990. This creates the more filled-in sound of the HD650's mid range. Wind instruments and bass guitars are excellent on the HD650. The mid bass has some bloom to it, and while not the tightest, lends well to drums, and synthesized mid bass with house, trance and dance music. The sub bass, however, is the HD650's weakest point in its low frequencies, as it rolls off after the lower mids. This makes it not the best headphone for genres that need a more filled in or neutral low end such as hip-hop and drum and bass, or genres with powerful drumming such as Japanese Taiko drums. Due to the lack of low end bass, but extra upper to mid bass, the HD650 has a somewhat soft or liquid sound to it. The extra upper bass gives the HD650's bass timbre a more chesty or "wooden" sound that lends well to African, Arabian and South Asian genres of music. 
 
Soundstage, while being good with depth, lacks the layering and precise imaging of other headphones. This gives the HD650 that characteristic "3-blob" dimension to its imaging. You hear music from outwards, up and down, but instrument placing and layering is not as distinct. I would say that for symphonic and orchestral music this is probably the biggest weakness of the HD650.
 
There are a number of alternatives to the HD650 one might wish to consider instead. The obvious one is its older but still produced sibling, the HD600. The two are basically the same headphone design, with the finish of the plastic being different color schemes, the HD600 being a little less expensive, different headband padding, and the HD600 cable being thinner and terminating to a 3.5 mm connector. Both have a similar, mid-prominent lushness to them, but the HD600 gives up some bass energy and trades it for a bit more treble, which gives it a more acoustic and orchestral-friendly sound somewhat closer to neutral. The two from what I heard are similar enough that owning both isn't worthwhile unless collecting is an endeavor. 
 
The AKG K702, Q701, and K701 are often compared to the HD650, but they are lean and bright enough that they should be compared more to the HD600 than to the HD650. I owned a Q701, and it is a completely different sounding headphone, with deeper but harder ear pads, lesser grip but a bumpy headband, a zazzy upper midrange, bright lower to mid treble, tight and neutral though dry bass and a soundstage with outstanding airiness, layering, texture, dimension and imaging that made the headphone excellent for jazz, orchestral and symphony, and acoustic music. Though the strong upper midrange made the Q701 a bit too aggressive at anything above moderate listening volumes for trumpets and saxophones, and women singers who sing at high and loud octaves (e.g. Adele, Rebecca Ferguson).
 
A fairer comparison would be the newer K712 Pro, or the K702 65th Anniversary Edition, as their sound is more comparable to the HD650. I have compared the HD650 to my brand new AKG K7XX Massdrop Edition that is tuned to sound similar to both the K702 Annie and the K712. Compared to the HD650, the K7XX is more comfortable and less tight fitting. The K7XX has more treble and more sub bass, while being a little more withdrawn in the mids than the HD650. The K7XX like most AKGs is highly source-dependent. It will sound like garbage on garbage recordings, and it will sound sibilant on poorly matched systems, unlike the more source-forgiving HD650. I will be writing a more detailed comparison review of the K7XX and the HD650, so more comparisons will be found there. 
 
The closest Beyerdynamic for comparison is the DT990, as the DT880 is flatter and more comparable to the HD600. The DT990 Pro is less expensive than the HD650, and has a prominent u-shape to its sound, with very dynamic and bright treble, deeper and more rumbling sub bass and mid bass, a wider and more open soundstage, and a more scooped midrange. The HD650 is definitely the softer and more laid back of the two, and the DT990 the funner, more exciting sound. Both make excellent complements to one another for different listening moods. The DT990 Premium models are a little more neutral, with the DT990 Premium 600 ohm having the smoothest treble of the 990 models, and being the closest competitor to the HD650 due to its refinement. 
 
In the planar range, Hifiman's HE400i is priced at the same 500 dollar mark as the HD650. From what I have read, the HE400i has a strong clamping force, is somewhat heavier, has deeper extending and tighter bass, and the treble is more energetic. 
 
Another option to consider is the recently released Philips Fidelio X2, which according to reviews from owners, has a tighter and more present low end than the HD650, a more neutral treble, and a wider soundstage. 
 
While the HD650 at times can be soft sounding and isn't the most comfortable for long listening sessions, it nonetheless will remain a staple headphone in my fleet. I'm interested in seeing what upgrades to DACs and better tubes will do to improve refinement. 

 
The Sennheiser HD 650, quite possibly most popular can in head fi. While IMO it doesn't live up to the hype, at it’s price point it’s the easy listening headphone to beat. Though the older HD600 is possibly the better option as it's cheaper and more balanced.
 
Unboxing
Pros: comes with a box, and a ¼ to ⅛ inch adapter
Cons: box too huge, lack accessories
 
Nothing much to say except taking off the gray  textured wrapper is a tad annoying, but I do appreciate the adapter. Often you have to buy that separately.
 
3.5/5
 
Burn in (modding?)
Pros: cons all go away in a few days, removing the foam takes out the veil.
Cons: veil highs, trident soundstage
 
On first listen, while the headphones gave me great bass and mids. I wasn’t too satisfied with the highs, and the soundstage felt too three point to me. Meaning the the sound is clustered either to the extreme left, right and in the middle. But over time the soundstage gaps are filled in, and removing the inner foam improved the highs a bit. No big deal
4/5
 
Design
Pros: clean gray design, metal grill and the driver behind it looks quite futuristic,
Cons: looks a bit cheap
It’s function over form, but I do like the look of the grills and the drivers behind it. And at worse it’s just plain looking. Not ugly in any way whatsoever.
7.5/10
 
Build
Pros: sturdy, nice metal grills, nice flat cable, easy to remove cables and ear pads.
Cons: made of cheap slimy plastic
 
If you can get past the cheap plastic part, its build is quite nice really. It’s very sturdy, and honestly feels like it could take a beating. And the easy to remove cables and pads are still very rigid and reassuring. The cable itself is substantial and doesn't tangle either. Definitely function over form.
8/10
 
Comfort
Pros: Perfectly snug, very light.
Cons: might be too snug for some, but I like the reassurance.
Hands down the most comfortable headphone I tried extensively. It’s snug enough so that it doesn't move around when I turn my head, but it’s not too snug to hurt said head. Still with others talking about it’s death grip, YMMW.
Outside of the snugness, you barely feel it on your head due the it’s thick band padding, soft velour pads and light weight. Utter perfection for me.
10/10
 
Sound
Pros: Warm euphonic mids and bass, Stellar mid/bass detail, Good soundstage and imaging at it’s price point, Laid back dark sound signature is very inoffensive.
Cons: A tad rolled off at sub bass and highs. Highs lack a bit detail and sparkle. Very polite leading to distant sound presentation.
It’s really a mixed bag for me. On one hand it has one of the most pleasing mids and bass presentation I even heard. It’s warm sound and offers that tube like euphony that is quite pleasing to the ears. And it’s dark signature means I never have to deal with harshness or sibilance. But you do miss a lot of the highs and while the bass is has good punch and detail, the lack of bass extension means it loses a bit of the sub bass rumble. And adding the fact that it’s a polite sounding headphone, it won't even get fatiguing to listen to, but it does sound boring. If there’s one word to describe the sound, is that it’s comfortable. Throw in the fact that it’s actually very comfortable to wear, and this is the type of headphone that you can listen for eternity and will never cause you discomfort.  But that strength is also its main weakness. It’s too polite and recessed sounding, everything just sounds boring with all the engagement sucked out.
 
On the other hand the Sennys do have good soundstage and decent imaging. Pretty good in its mid fi price range. But it doesn't excel compared to higher end headphones as the speed it a tad slow (though nothing particularly bad). The mid and bass detail however is quite excellent.
 
8/10
 
Conclusion
 
You know listening to the sennheiser hd 650s is kinda like listening to a live performance under three thick warm blankets in a cold day. Sometimes you just want to pull those sheets over your head and have the sound lull you to sleep, But other times you just want to throw away those blankets away and be engaged to the music potential harshness be damned.
 
As it is, it’s a niche headphone for the kind of person that’s sensitive to harshness and wants a warm, euphonic and detailed (minus the highs) passive listening experience.
 
And provided you don’t mind a polite sound, it’s quite good with most genres.  But like the akg 271s I had before (though to a lesser extent) it’s just a bit too polite for me to enjoy in most situations.
 
 
41/50

My time with the HD650 was short: bought on Amazon and returned 6 days later.
 
Prior to serious listening, I 'burned-in' the headphone for 48 hours with constant pink and white noise. This did improve the sound, firming up the bass and eliminating some perceived hollowness.
 
The thing that struck me first about the sound of the HD650 was its sumptuous smoothness. Vocals especially had this syrupy sweetness which many enthusiasts will like about the HD650, but for me just masked the natural characteristics of the human voice. I find it difficult to understand why recording studios would use this headphone, as Sennheiser claims in its advertisements, when vocal presentation especially, is so obviously coloured. When I listen to a headphone I want instruments to sound as close as possible to 'real life' instruments, timbre being particularly important. The HD650s do manage to preserve some accuracy in instrumental timbre but simply fail on the human voice, where neutrality is traded for chocolate-smoothness.
 
The overall sound is indeed warm and smooth which is sometimes appealing, but together with the relaxed, sometimes listless presentation, music is robbed of the vitality and vivacity it needs. This does make the HD650s the headphone to go for if you just want to listen to music in comfort for hours on end; but some of us want some energy and excitement - when the music demands it - which these headphones frequently fail to deliver.
 
Bass is quite deep and usually remains fairly tight, but sometimes sounds soft in some music, which is I think is a consequence of the overall 'plump' warmth of the headphone. And again due to the - for me - suffocating smoothness, the high treble sounds blunted; the HD650s never manage to reach the heart-stopping heights that the female voice especially, is capable of.
 
 
As for other qualities...imaging is good but nothing special, nicely formed but by no means holographic. Sound-staging is very good, in fact it can be ruthlessly revealing of poor quality source material in that regard; some of my less than perfect recordings had a 'gap in the middle' effect on the HD650s which was not apprarent on other headphones.
 
Detail retrieval is excellent. The HD650s are able to pick up background and ambient sounds with ease and elegance, but musicality always taking precedence over outright detail-scavenging.
 
As for build quality, really disappointing - masses of plastic that has an uneven appearance in certain lights; and they look as if they could easily break or crack if dropped on a hard surface or accidentally sat on.
 
So I recommend this headphone to someone who a favours a warm, smooth and 'friendly' representation of music. But those who want crave neutrality, realism and energy - look elsewhere.

These headphones are a true classic!  Even if they are bettered today by some in technicalities, their sound signature and non-fatiguing nature remain a must hear in today's very crowded mid-fi range.  However, you'll need a good source (they're quite forgiving on the quality of the recording though) and an amp that can drive them to their full potential since they scale very well with high end amplification (in my case the ALO PanAm dac/headphone amp).