Sennheiser HD 650 Headphones

Great headphones , not too far behing the best cans out there for much less. Sound better when balanced and with aftermarket cable.

So it has been quite a while since i've had these headphones(about 7 months or so), so I figured it was time to write a proper review, to the best of my knowledge.
Allot has already been said about these awesome set of headphones, so i'll focus on my personal experiences.
Please note, I am not a seasoned audiophile, i've only owned quality audio gear for about 2 years.
 
First off, the package:
It comes in a cardboard box, as most products, which I frowned uppon a little, considering the price. But once the cardboard is removed, a quality ''hinged'' box is revealed, which really adds to the unboxing experience. It is like opening your 18th birthday present, something really special. 
As for the contents of the box: it doesnt feel extra premium, but it does feel like you have bought a quality product. The foam packs the headphones in nicely, and is not bad on the eye. 
 
''Alright, enough about the package.. what does it sound like?''
First off, I should list my DAC, which is a https://www.mayflowerelectronics.com/shop/mayflower-custom-products/desktop-objective2-with-odac/ . Which is one of the most, if not the most neutral DAC's out there. Meaning that it doesn't alter highs/mids/lows(bass).
Second, the headphones that I own, and can compare it to, are: Sennheisser HD280(more then 12 years old), and the Sony MDR-1RBT(recent purchase, after HD650). I also own two 5.1 sound systems, one being a basic pc speaker system from Logitech, and the second being a fairly decent system for the TV, called Sony BDV-N590. And a JBL Extreme(bluetooth speaker)
Considering all these audio systems, I will now give my impressions of the HD650 Finally.
 
Using only Foobar2000 music player, playing FLAC music, and Spotify Premium(for quality) for the music unavaiable on FLAC, I listen mainly to Pop, Rock, Country, Rap R&B and Worship(christian) music.
The highs are clear and defined, especially when listening to Rock music, but it works for every type of music. 
The mids are always present, meaning that the HD650 doesn't miss a chance to display its excellent range. It really doesnt miss a beat. 
The bass is always viewed as ''less present'' in Sennheisser headphones. To be honest, I am not so sure... the bass sounds great even when compared to the subwoofer in my TV set. Which fills a 6*6 meter room without even breaking a sweat.
More important is the clearness of the sound. There is NO distortion, even at high volume levels. And it feels to me as if the drivers aren't even trying.
Another thing about sound: you'll be able to hear people talking to you, because of the open back design. I have many conversations with friends and family while wearing these headphones. While a little dimmed(as expected with headphones), I really didn't have to try hard to hear any of them.
 
To summarize the sound quality:
Highs/Treble: +++ Superior
Mids: ++ Very good
Lows/Bass: ++ Suprisingly good
All in all these are the best headphones I have listened to myself. Even compared to an hour long session with the HD600, provided by a friend's father.
 
Design and feel:
This is where these headphones get a ''-'', in my opinion. The sound may be superior, but the plastic headband really doesn't reflect this sadly.
It makes it feel cheap whenever you put it on. That is untill you turn the sound on, that is..
Also, the double cables WILL TWIST, unless you are prepared to invest in a more expensive third party cable.
However, these headphones are insanely comfortable. I can wear them all day long without any discomfort.(using standard vellour earpads). 
 
Conclusion:
 
These headphones are my go-to system for listening to music at home. I havent used any of my 5.1 sound systems seriously since purchasing this gem.
It sounds like a dream, and that's giving it less praise than it deserves. Even the sony mdr-1rbt headphones wired up(no bluetooth at home), dont come even close.
 
If you want only quality sound. below flagship price, these headphones are the ones to get. 

Audiophile world can be your salvation or your hell. It depends how deep you will be sucked in and how confused you are what you’re looking for. For me it has been both. It all started two years ago when my old headphone broke on me and I had the wild idea to press the “buy” button on $1000 headphone called Grado GS1000.
 
I remember holding them in my hands with watery eyes upon the sight. The texture of the mahogany the smell of the wood it was something retro and to behold. Everything about that headphone was unique and I was excited to try them out. Then the disappointment when I found out that it was lacking in comfort and bass. How can a $1000 headphone be lacking in anything? Is the audiophile world about just sound or is there more to it? Just when you get a Porsche 911 do you expect it to perform great in every category considering its price tag?    
 
The answer is no. The audiophile world is more than sound its world of senses such as visual, emotion and imagination. The GS1000 was beginning of the end as I took on a journey to find my headphone that will take me on a journey each and every time. I bought few other headphones such as HD800. T1(Gen2) and few others until I discovered the HD650. Or maybe we can say HD650 found me.
 
I got the HD650 on a sale for $299 which is ¼ price tag of other flagships I previously owned. Yet this baby makes me happy. The mid-range is possibly the best I’ve yet heard. To my ears not recessed one bit with extremely balanced and textured imaging. Also the bass is very satisfying it does not bleed into mids.  Possibly the greatest quality of this headphone is the slightly tamed high frequencies which makes it very forgiving main headphone (Spotify Premium, YouTube, Netflix). This is everyday audiophile headphone that can be your last audiophile headphone considering its audio reproduction qualities.
 
HD650 received many positive reviews from both professional and amateur audio enthusiasts and I believe it is well deserved. This is a subjective review of a guy who is so impressed with the quality for $ that I had the urge to write this review this Saturday morning over cup of warm coffee.
The only weakness I can think of is that in stock form clamping force can be little on tight side but is easily corrected. Just expand the headphone all the way and unbend the metal slightly. Do not unbend the plastic because it will break. After this comfort is nearly perfect.  Pads also could be memory foam but they are not uncomfortable overall.
HD650 deserves to be heard.
 
Now let’s get back to drinking the coffee and bagels.  
 

 
 
 
 
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I like my HD650.  I have always liked the Sennheiser sonic signature and I was immediately impressed after using the HD555 for a couple of years
 
But then after awhile; after some A/B comparisons I heard the famous HD650 veil.  There seemed to be less treble response than the HD555.  Yes there was definitely more detail and Bass, but after A/Bing with the HD555, I became a bit annoyed. My parents have a cheap triple port headphone amp connected to the TV for $40.  When I connected the HD650 to it, there was no treble response.  This is where impedance matching is really important and something, that most people who dis the Sonic Veil of the HD650 don't understand.
 
So i decided to buy a Class A amp from Firestone (as we don't have much choice in Australia) , the Libby, and the veil disappeared. In fact now they sound bright.  
 
So now I really enjoy them.  I do connect them to my Fubar III (Class A/B) occasionally and can hear the dullness returning, even with the high impedance setting. I dont think I need to replace the stock cable as they are bright enough as it is.  I would rather use that money to purchase the HD800 or an AKG.
 
I really personally believe that the veil became an urban legend because people were or are hooking up to either poor amps or no headphone amp at all. I read quite regularly on these forums that people say that headphone amps are useless, but if you really want decent sound and spend a fair but on headphones you really need to get an amp.
 
I like the sound of open headphones because I live in a quiet area and don't need to isolate the sound.  The headphones are extremely transient. 
 
I dont regret buying them at all
 
 

An excellent sounding headphone for the price. The 650 is what separates a mid-fi headphone and a hi-fi headphone. It is has extremely rich bass and excellent mids. The headphone does require a little amplification, but it is not too difficult to drive. The headphone is extremely comfortable- when broken in. when you first get the headphone, it clamps a little hard and the earpads aren't very soft, but both loosen over time. Some people may not like the "dark" or more warm sound, in which case they go for the hd 600, but if you do like the warm but not overly warm sound this is a extremely good headphone. It sounds excellent for classical/jazz, acoustic, rock, and metal. The bass is creamy yet slightly punchy, the highs aren't piercing but aren't laid back. The soundstage and natural reverb the headphone adds is sublime. Once the headphone pads wear in the comfort is unrivalled. 

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. 

I listen to alot of heavier music dubstep through metal. I also enjoy listening to the beatles and Classical music! These Headphones shine for lighter more care free music, but when i try to give it a true load and demand heavy notes from the bass it doesnt show up. I have a oppo ha-2 amp to go with these and i have to use the bass boost for anything heavy and then they sound fine. Without the bass boost i really struggle to hear it at all. Im not a bass head by any means. I thought the Audio technica mx-50 was way to over powered in the lower end. I love my HD 650's and they are a great start for any audiophile! They are classic!

I bought these to enjoy and to assist development of a headphone amp, having owned Sennheiser phones in the past, the last being HD518s. First impressions on unpacking are of fairly ordinary appearance and materials although actual comfort is first rate. First impressions of sound are that they sound a little thick and subdued. I can understand why people could be disappointed; there are plenty of cheaper phones which impress more for the first minute or two.
 
However these are dark horse headphones. Although their overall presentation is mellow, and some would say veiled, they are incredibly revealing in reality after prolonged listening. Get the source and amplification right and they even do rock really well. They are not really suited to mediocre source equipment since they add little drama or coloration to things. The midband is remarkably even and subjectively lacking in obvious resonances. You will readily hear the affect of altering items in your source chain, and indeed in changing parameters and topologies in your amplifier. Although the balance is warm, they are not that forgiving of poor source material. Instrumental timbre is rich and detailed, although, again, it tends to take time to appreciate this, as it is not presented in a way that grabs your attention immediately.
 
Voices are cohesive and have natural body. Here IMO it is easy to spend more and get less. Power handling and linearity at high levels are excellent, although at 300 Ohms you will need volts to get them going; portable devices are unlikely to satisfy here. On rock, they actually tend to come alive at higher levels; there are probably better choices if you prefer to listen quietly. Leakage is predictably high. 
 
A 'mature' design but definitely still one with a lot of appeal.

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

These cans are exquisite. I can literally fall asleep with these on. This fact is cheifly assoiated with their velour ear pads. And in regards to sound, their sound quality is immearsive. No singular element of their sound is deprived. I can state that they're immaculately endowed with mid-range presence.
Bottom line is. if you can afford the admittance fee these will grant you auditory bliss.

Overview:
 
The Sennheiser HD 650 is a headphone I've owned more than once and always seem to go back to and a headphone I'm very familiar with and have tried on countless different systems from low-end to summit-fi. In terms of systems I've owned, I mainly used them on mid-fi gear. This is a headphone I have owned 3 times now, because I always found something I liked about it, but there are a few issues that ultimately have caused me to let this headphone go in the past, and the only reason I currently own them is due to getting them from a friend. This review is quite positive overall, but I honestly find them a bit exaggerated in how good they are and I don't really find them to scale up as much as many claim. Basically I don't quite find these to be the giant killers they are often touted to be. 
 
Other headphones I currently own:
AKG K7XX
Audioquest Nighthawks
Beyerdynamic DT 990 Pro Limited Edition
 
Gear I'm currently using on the HD 650's:
Project Sunrise III
Sony UDA-1(Amp/USB DAC/Optical DAC).
 

 
 
Gear I used to own and used extensively on the HD 650's:
Schiit Lyr 2
HRT Music Streamer HD
 

 
Build and Comfort:
 
This headphone is quite well put together, I would say it's about average for it's price range, but it is very modular which makes it very easy to fix and replace parts with. Comfort is good, but can be a mixed bag for some people. People with large ears that protrude may have issues with their ear-cups and their clamp may be a bit too much for those with large heads but it lessens with use.
 
Sound:
 
The main focal point of the review, it's going to be broken up in various sections. 
 
Tuning: The tuning of the HD 650's is one of it's strongest points in terms of it's sound quality and honestly the reason the headphone is so beloved by so many people. The tuning of the HD 650 is among the best among open headphones and it's very even and smooth, I find it has slightly too much presence in the upper mids on most systems to my ears and it doesn't have enough sub-bass. Other than those two small complaints it does amazing on the tuning. It has a euphoric and addicting tuning to it. I did find the bass to be a bit lacking in terms of definition and overall quality.
 
Imaging: This is where I start feeling a bit mixed on this headphone, it's just average in it's price range and I think some of it's competition do imaging much better overall, especially planars. The imaging has a slight smear and fuzziness to it overall which I finds ultimately prevents the sounds from having as good definition of instruments as it could, it does have an edge on imaging over the HD 600 though.
 
Soundstaging: This headphones has a moderately-large sized soundstage with quite good depth, decent width, and no issues with the center imaging. Notably bigger than the HD 600's soundstage but a smaller than the Nighthawks and K712s. I find the size around that of the DT 150, DT 990 LE, or K612. The soundstage isn't the most dimensional sounding, better than some headphones such as the K7XX which honestly lacks a bit of dimension and body to the sound. It doesn't give the really 3D holographic effect in it's soundstage like the DT 150 or Nighthawks did.
 
Detail: The detail on this headphone is just alright, like it's imaging it's just average. I find it somewhat lacking in detail compared to a lot of it's competition, especially planars.
 
Transparency: This is another aspect of where this headphone shines, you often just forget you are listening to headphones with these. I rank these as the 2nd best headphone I've owned in terms of transparency which is saying a lot. I rank them slightly above the DT 150 in this aspect as the DT 150's slightly uneven response can distract you from time to time. I rank them below the Nighthawks as I found I don't forget them quite as often as the Nighthawks as I find the HD 650's harsher and more brittle in the treble, nor have I ever gotten the same level of realism from the HD 650 as the Nighthawks.
 
Clarity: These headphones have quite good clarity, I would rank them above the AKG K712 and AKG K7XX in this aspect as the AKGs have a veil in the 2-3khz region of their sound. Compared to the DT 150 and the Nighthawks the HD 650's lack clarity and the HD 650's are somewhat smeared and fuzzy in comparison. I wouldn't call these headphones veiled or non-transparent though. The HD 650 sounds a bit fuzzy and gritty to my ears which I found takes away from a truly black background.
 
Dynamics & Body: Dynamics and body I have found quite key in terms of achieve ultimate realism, especially with explosive and/or deep sounds such as drums, thunder, deep subtle rumbling, etc. Their somewhat rolled-off sub-bass does take a bit away from a more solid foundation of sound. I have found dynamics nad body to be heavily dependent on the system, I found the Lyr 2 with the HRT MS HD to of brought out a lot of dynamics and body on the HD 650. Dynamics and body are quite good on the HD 650's, about what I would expect from a good mid-tier headphone. It's not really going to create the sense of awe and power from it's dynamics like a very dynamic headphone such as the Nighthawks. Bass excursion is quite good, doesn't seem to audibly distort or break up easily and can crank out quite a bit of bass on certain systems.
 
Overall, I find the HD 650 an excellent headphone, it's the overall package that makes it a great mid-tier headphone to purchase and honestly would be one of my first recommendations to people. I don't consider this headphone a flagship by any stretch, but it really comes down to what people want out of their headphones. I think it has it's flaws mainly in it's imaging department, a bit of a lack of a bass foundation as well as some lack of quality in bass, some lack of clarity, and mediocre detail reproduction. I don't honestly think these are worth the MSRP as they are getting stiffer competition as time goes one, but if you get a good deal on these I wouldn't hesitate to recommend them. 

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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

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 :=)

Driving Miss Daisy? For those of you who have seen the movie you might get the analogy.

You hear a lot on HiFi forums regarding the Sennheiser HD650s. Phrases like ‘legendary’ abound in many amateur (and some professional) reviews and you get the impression that these headphones are the best thing since sliced bread. Glowing superlatives regarding sound stage, imaging, bass control, detail retrieval are there in droves. I own the HD580s and love them so eventually I bought a pair of the 650s just to see what the hype was all about. And my initial conclusion after running them in was just that – hype!

Running the 650s through my Burson Playmate 2 what I heard was definitely underwhelming.

Bass – somewhat bloated, not well controlled and it rolled off in the upper levels. Some slam but not really enough and they didn’t go low enough without losing definition

Midrange – smooth, almost urbane but vocals didn’t impress as they often sounded a bit timid

Treble – definitely dialed back and taking all the fun and excitement out of lead guitars

Imaging – three blobs of sound (left, centre and right) that seem to meet up at the edges

Sound stage – narrow and compressed with no depth

Detail – what detail? Things I’d heard on cheaper cans just weren’t there.

So I went back to the reviews and wondered if the pundits were using the same cans as me. Why were these reviewed so positively, what were the factors that made these supposedly so good for the money? After a while one factor from my research began to stand out - scalability - with driving power a major aspect. Quite simply what they were saying was you need the right amp. To cut a long story short it became evident that my PM2 (a great DAC/Amp) that while being classed as powerful still didn’t have the chops to get anything near the best out of the HD650.

Enter the Schiit Asgard3 which I bought just to see what the HD650s could do – not something I’d normally do. With four times the power of the Burson and recommended by many it was also a reasonable price. Would it prove the HD650 fans correct and bring them to life? The answer is Yes.

I’ve spent a few weeks with the HD650s as my only listening device. I wasn’t trying to make comparisons so no need for my Audeze LCD1, HD580s, etc. I just wanted to hear what the Asgard3 did to the 650s without having another set of headphones colouring my opinion. So why did I say yes, what’s improved? Let’s go back to my original criteria

Bass – possibly this is where the biggest improvement is for these Senns. Slam, good definition (but it doesn’t quite go all the way down) and the roll off has been minimized to the point where you don’t really notice it. It’s not bass head stuff but it’s enjoyable and it’s definitely faster and tighter.

Treble – Yay, there is now some sparkle and you definitely hear it on the upper registers of guitars and similar instruments. What’s more it’s cleaner and tighter without getting peaky.

Imaging – also a huge improvement. The three blobs are gone and the whole sound stage is now covered albeit with one or two little dead areas.

Detail – of course with improved imaging then those little details that I couldn’t really hear using my PM2 have emerged.

Midrange – you’ll notice I’ve left this for last as, for me, there are some ambivalences. Often touted as one of the HD650s strengths it’s also a bit of an achilles heel IMHO – or at least with this set up.

The midrange is warm, smooth, almost beguiling. It’s at it’s strongest in the lower mids and I feel that this is to the disadvantage to the higher registers of the midrange which don’t project anywhere near as well. The mids seem to try to smooth over recording imperfections and a good example of this is vocal sibilance which is usually caused by poor use of a mike and a lack of basic vocal technique. I imagine that this drives recording engineers nuts as it’s almost impossible to correct without compromising the recording. On Mary Black's beautiful rendition of ‘Bright Blue Rose’ you can hear the sibilance on just about every set of cans I’ve ever used except the HD650s. The other effect of the somewhat recessed upper mids is to push many vocalists into the background. Imagine that they have taken two or three steps back towards the drummer and are singing from there – that’s the effect that I hear. And it’s also this effect, along with those slightly recessed vocals and the ‘smoothing effect that gives rise to the old chestnut, the Sennheiser 'veil'. I don’t think the A3 has totally removed it.

In conclusion, yes, I believe that these cans definitely scale up when paired with an appropriate amp and what the Asgard3 has done has made the 650s a keeper for me, they now sound great with above the caveats above excepted. The Audeze LCD1s I own blow these out of the water in just about every department but we are talking two different beasts here with quite different sound signatures so the comparison lacks some validity.

I’ve yet to hear all that some claim these 650s are capable of but do I want to spend a disproportionate amount of money for an amp considering the cost of the 650s to find out? No, I’d rather get a better set of headphones and preferably ones that are not so picky about the amp.

The Sennheiser HD650 is a great pair of headphones. Makes a great complement to airier headphones.

The HD650's don't do anything really wrong.
They have a natural sound signature and slightly elevated midbass that is easy on the ear (non-fatiguing).
Most people will find that they appreciate their sound.
They are not the final word in transparency and speed, but they are advanced enough technically to allow them to be true to the source material, offering an excellent sonic window into the music.
This neutrality allows them to be used for reference purposes; as a studio headphone mixes done on them translate well to monitors.
Similarly, they sound great with all genres, and don't dominate any particular one.
 
For a beginner head-fi'er, HD650's paired with a <$500 SS amp and a cheap DAC might be the last headphone rig you ever need.
Inversely, the HD650 scales very well with upgrades, sounding best to these ears with a powerful tube amp.
However, If you don't like the sound of these phones on first (amped) listen, don't try change the sound signature with cable upgrades because the differences are relatively subtle.

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.

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.

My first Sennheiser was the HD555, which was a real gem for its price bracket, and then when it broke, I replaced it with the HD600. I immediately exchanged it for the HD650 as I found the HD600 to sound so similar to the HD555 (just a little bit more treble mainly) that the price difference wasn't justified. The HD650 is very similar to the HD600, but with a bit more weight in the bass, and a slightly smoother sound overall. But in any case, these upgrades are all diminishing returns, as the HD555 really is excellent already.
 
The HD650's clamping force is strongest of the three, but it's still comfortable enough that I often forget to take them off after I was done listening to something. The velour earcups are always the most comfortable to me compared to leather, pleather, or foam.
 
In terms of looks, the Sennheiser are probably lagging behind all the competitors, looking kind of drab and boring, while the HD800 takes things to the opposite extreme, looking like some science-fiction head gear.
 
I quite like the Sennheiser sonic signaure, which many people refer to as being relaxed, or veiled. I think of it as being very smooth and non-offensive. The treble and upper mids never get fatiguing or too bright, and the overall tonal balance is very good, with nothing sticking out or recessed in any of the frequency ranges. The sub-bass rolls off around 30Hz and I wish the HD650 had more extended sub-bass and weight, since that's what it needs in order to sound like a full-range speaker system. The Audio-Technica ATH-M50, ES-10, and Denon AH-D7000 all do this very well--sounding like there's a subwoofer in the headphones. The treble of the Sennheiser is nice and smooth and articulate, but it seems to lack just a little bit of that airiness that audiophiles really love.
 
Overall, I tend to think of the Sennheiser HD5xx/6xx series as workhorse headphones that sound great, are very comfortable, and are never offensive. They may not win awards for looks or have that really high-end "magical" hi-fi sound, but they are tonally well-balanced and very pleasant to listen to.

Superb