INTRODUCTION

Back in January 2014, I wrote a comparison piece on the two Sennheisers I owned at the time (the HD600 and HD700) which proved to be relatively popular read - http://www.head-fi.org/t/725127/comparison-review-a-tale-of-two-sennheisers-hd600-vs-hd700.
 
In that comparison I learnt that I appreciated the HD600’s more neutral and natural presentation over the excitement, edginess, and expansiveness of the HD700. Following the review I was asked a few times how the HD650 would compare to the HD700 (as both were said to have a darker, warmer tonality compared to the HD600).  Unfortunately it was a question I was unable to answer – as the last time I’d heard the HD650 was at least 4 years ago when I was in NY auditioning the HD600 and HD650, and deciding which to buy.  A lot of water has flowed under the proverbial bridge since then – and although I’m not in the position to compare the 650 and 700, I have been lucky enough to borrow a 650 for a couple of weeks.  This gives me a great chance to renew my acquaintance with the HD650, and perform an in depth comparison with my HD600.
 
I’d like to extend hearty thanks to Head-Fi member (and fellow kiwi) 62ohm (Rizki) for parting with his HD650 and allowing me a chance for this comparison.  I of course am going to reciprocate with him once I’ve finished – I know he’s looking forward to trying my HD600’s on his HDVA600.
 
So take a stroll with me on a journey of discovery, and see if my tastes have changed over the last 4 years, and if I’m still happy about the decision I made when I chose the HD600 over its doppelganger – the HD650.
 
ABOUT ME (or a base-line for interpreting my thoughts and bias)
I'm a 47 year old music lover.  I don't say audiophile – I just love my music.  Over the last couple of years, I have slowly changed from cheaper listening set-ups to my current set-up.  I vary my listening from portable (Fiio X5, X1 and iPhone5S) to my desk-top's set-up (PC > coax > NFB-12 > LD MKIV > HP).  I also use a portable set-up at work – either X5 > HP, or PC > Beyer A200p > HP.  My main full sized headphones at the time of writing are the Beyer T1 and Sennheiser HD600.  Most of my portable listening is done with IEMs (I do also have the Beyer T51p, but IEMs command most of my portable time) - and up till now it has mainly been with the Fidue A83 & A81, Dunu DN-1000 and Altone200. A full list of the gear I have owned (past and present is listed in my Head-Fi profile).
 
I have very eclectic music tastes listening to a variety from classical/opera and jazz, to grunge and general rock.   I listen to a lot of blues, jazz, folk music, classic rock, indie and alternative rock.  I am particularly fond of female vocals.  I generally tend toward cans that are relatively neutral/balanced.  I am neither a bass nor treble head (you could argue that I do like clarity though).  I am not treble sensitive (at all), and in the past have really enjoyed headphones like the K701, SR325i, and of course the T1 and  DT880.
 
I have extensively tested myself (abx) and I find aac256 or higher completely transparent.  I do use exclusively redbook 16/44.1 if space is not an issue.  All of my music is legally purchased (mostly CD – the rest FLAC purchased on-line).
 
I tend to be sceptical about audiophile ‘claims’, don’t generally believe in burn-in, and would rather test myself blind on perceived differences.  I am not a ‘golden eared listener’.  I suffer from mild tinnitus, and at 47, my hearing is less than perfect.
 
This is a purely subjective review - my gear, my ears, and my experience.  Please take it all with a grain of salt - especially if it does not match your own experience.
 
I have used the HD600 extensively over the past 4 years (owning it separate 3 times), but this is my first reintroduction to the HD650 for some time, so I may miss some of the intrinsic strengths it brings to the table.
 
REVIEW / COMPARISON RESOURCES
 
 
For the purposes of this review and comparison, I used both headphones mostly from my NFB-12 + LD MKIV.  Both headphones were volume level matched using an SPL meter and calibrated (twice) with a constant 1 kHz test tone.  This was rechecked periodically during the comparison.  I used the Little Dot mainly because it was easier to swap with the correct volume matching (more precise markings on the pot).  Tracks used were across a variety of genres – and can be viewed in this list http://www.head-fi.org/a/brookos-test-tracks.
 
PUBLISHED SPECIFICATIONS
 
FREQUENCY RESPONSE GRAPH
 

Thanks to Headroom.
 
PACKAGING
 
 
Both HD600 and HD650 come in the usual high quality (very large) foam padded hard hinged box, with a printed outer cardboard sleeve.
 
BUILD / COMFORT
 
Both headphones are very virtually identical in build, and I know from my own experience with the HD600, that with proper care, it can last for a decade or more.
 
 
The following applies to both HD600 and HD650.  Both headphones have a moulded hard plastic shell, with steel extenders, velour pads, and soft foam headband padding.  The greatest thing about both the HD600 and HD650 build is that they are completely modular – from the removable cable to the drivers.  This makes it very easy for the owner to replace individual elements – prolonging the headphone’s life.  On my previous HD600, I had already replaced the headband, pads, headband padding, and both drivers – all easily ordered direct from Sennheiser, and fitted myself.
 
 
The one weakness in the HD600/HD650 design is the headband itself.  It looks solid, and I read (with my first pair) that it was carbon.  It’s not - it’s molded hard plastic.  New HD600/HD650s are quite clampy.  So I thought the headband would be stronger than it actually is.  So I stretched it – and – SNAP!  OK – my mistake (and an expensive one).  Word to the wise – if you want to relieve the clamp force, fully extend the metal extenders, and bend those only.  You live and learn.
 
 
The major noticeable difference between the two headphones (besides the colour) is the cable.  The HD600 cable is functional – but relatively “light” in build.  The HD650 cable is better built.  There is (to me) no audible sonic difference between the two.  The HD600 also has a plug with built in adaptor, whilst the HD650 plus is a standard 6.3mm.  If I had my preference, I’d like the HD650 cable with the HD600 plug.
 
 
As far as comfort goes – there is no noticeable difference between the HD600 and HD650.  Rizki’s pair of HD650 is a little newer and has a little more clamp – but still remains quite comfortable.
 
 
Both the HD600 and HD650 are very light weight, and on both headphones the pads measure (internal space) 7cm x 4cm with a depth of 2.5 cm.  They completely enclose my ears and there are no issues with my ears touching the driver foam.  I can literally wear either pair for hours.
 
SONIC COMPARISONS
 
General frequency summary (supported by graph above):
 

 
 
These were my general notes before actually downloading the graphs from Headroom.  The HD600 to me has always sounded neutralish (maybe a bit flabby in the bass at times), but always a very natural headphone.  I played guitar in my youth, and also attended a lot of concerts.  My mother and grandmother both played the piano.  The HD600 just flat out nails how each of the above mentioned instruments sounds live – no pretensions, no spotlighting – just how the actually sound.  It may not be quite as flat from bass to treble (neutral) as a headphone like the DT880 – but to me it has always sounded a lot more realistic. Because of its tuning – it also has an airy top end without being peaky.  Plenty of detail – without being pushed in your face.
 

 
 
The HD650 (from my memory of it 4 years ago) was similar to the HD600, but darker, bassier, with less air.  The funny thing is that now I have the two in front of me, with my gear, and the ability to volume match, I’m finding those early impressions are not as accurate as I once thought.  For a start, I’m not finding the HD650 dark at all – in fact they seem to be every bit as nimble as the HD600. Tonally they are a fraction short on air, and they also have a fraction more bass – but we’re not talking about big margins here.  The most noticeable difference is that the HD650 just sounds slightly softer – not quite as etched.
 
Soundstage / Imaging:
 
To test soundstage and imaging I’m using Amber Rubarth’s “Tundra” track from the album Tales of The 17th Ward.  The track is binaural – so it gives good queues anyway – but can be very good for a combination of imaging and soundstage width and depth. 
 
Both the HD600 and HD650 display very similar soundstage size – in width and depth and height.  One of the great things I’ve always liked with the HD600 is that whilst the soundstage size isn’t as expansive as AKG’s X701/702 series, or my T1 – it does sound accurate for most music.  As a result  most music I listen to with the Sennheisers sounds incredibly natural – and imaging is definitely not left/center/right – but rather more evenly spaced within the stage.  The HD650 mirrors these same traits, and switching between the two doesn’t change the overall imaging.  Apart from the subtle tonality differences, I could be listening to the same headphones with this test.
 
Switching to Loreena McKennitt’s “Dante’s Prayer” (with the HD650’s in place), and I’m at my usual spot in the audience – around row 2 or 3 back.  Loreena is center stage, and that beautiful cello is sitting slightly back and over to the right.  Again the HD600 and HD650 are too close to tell apart. On this particular track, when the song ends, the applause has always been so natural and enveloping (with the HD600) that I can close my eyes, and for a moment I’m actually in the audience.  The HD650 handles this with aplomb – and I’m there again.  It’s a magic moment – and one that both Sennheisers manage to convey easily.
 
Specific Genre Notes:
 
Rock / Classic Rock / Prog Rock – tracks tested included:

1. “Away from the Sun” – 3 Doors Down
2. “Art for Art’s Sake” – 10CC
3. “The Diary of Jane” – Breaking Benjamin
4. “Hotel California” – The Eagles
5. “Sultans of Swing” – Dire Straits
6. “Boulevard of Broken Dreams” – Green Day
7. “Elderly Woman Behind The Counter In A Small Town” – Pearl Jam
8. “Immortality” – Seether (unplugged)
9. “Money” – Pink Floyd
10. “Trains” – Porcupine Tree

 
The differences are extremely subtle, and more than once tonight, I’ve forgotten which headphone I’ve had on my head.  After a couple of minutes listening (once my ears have adjusted), it’s just not that easy to pick.  But with rapid switching a pattern is emerging, and it seems to be relatively consistent.
 
With the male vocals in particular, the HD650’s have a slightly deeper, slightly softer, and slightly smoother presentation.  It’s not that the HD600’s are grainy either – it’s just that they do have a slightly airier presentation.  I wonder if this is where the comment that the HD650 are “more refined” comes from”?  If it is – I’m not hearing it so far.  They both show the same level of ability and refinement, and the difference is in the slight tonality contrast.
 
Both seem to struggle slightly with faster music (Diary of Jane), but on the slower tracks, tonally both are very natural, and extremely enjoyable.  Switching to one of my all-time favourite Pearl Jam tracks, and I’m expecting two things – and am subsequently wrong on both.  I’m expecting that Vedders voice will sound deeper and better on the HD650’s, and they are both so close that it’s really had to tell them apart.  Yes the HD650 might be very slightly deeper, but the HD600 conveys the timbre of Vedder’s voice slightly better for my ears.  The second preconception I have is that the HD650 will not show the contrast of cymbals (there is a lot of it in this track) with the vocals – and yet the HD650 delivers in spades.  There is no sign of any veil that I can tell!
 
Verdict – too close to call.
 
Opera / Classical  - tracks tested included:

1. “Nessun Dorma” – Pavarotti
2. “Flower Duet (Lakme)” – Netrebko and Garanca
3. “Moonlight Sonata 1st & 3rd” – Wilhelm Kempf
4. “Op.8, No.1, R.269 "La Primavera" - 1. Allegro” – Anne Sophie Mutter & Trondheim Soloists (Vivaldi’s Four Seasons)
5. “OP 35 1st Movement from Tchaikovsky Violin Concerto in D” – Julia Fischer

 
Once again, the differences are so subtle that it becomes hard  to tell the two apart once they’ve been on my head for longer than 2-3 minutes.
 
Both shine with Pavarotti’s “Nessun Dorma” – and manage to convey the majesty of the master tenor’s voice.  But with Lakme’s “Flower Duet” there is the tiniest of differences.  The HD600 do show a little more air in both Netrebko and Garanca’s vocals – but the HD650 shows the slenderest bit more contrast (darker background – or am I imagining it?).  Either way though I could listen to this track with both headphones.  Coupled with the LD MKIV, the presentation is wonderfully captivating.
 
Moving on to Moonlight Sonata – and both Sennheisers performed with distinction.  My grandmother loved the 1st movement of this sonata and played it often.  She would have loved this recording on either headphone – but maybe the HD650 gets a slight nod for the timbre portrayal.  We’re talking preference here though – as both sound wonderful.  Both also performed extremely well with the Tchaikovsky and Vivaldi pieces, and preference would be again up to the individual.  My preference was for the very slightly airier performance of the HD600 here.
 
Jazz – tracks tested included:

1. “So What” – Miles Davis
2. “Gaucho” – Steely Dan
3. “Safer” – Gabriella Cilmi
4. “Love Me Like A Man” – Diana Krall
5. “Ruins” – Portico Quartet

 
For the first time during testing the tonality of the two headphones was easier to tell apart.  With Miles’ trumpet, the HD600 was a tad strident at louder volumes compared to the HD650 (when listening at lower volumes these differences faded).  Portico Quartet’s “Ruins” was a little dark and broody on the HD650 though – and I personally found the HD600 was the slightly easier listen.
 
Switching over to female vocals and the standout track for both headphones was Gabriella Cilmi’s “Safer”.  I know this is more Pop than Jazz – but her voice simply has that jazz undertone.  Both give wonderful presentations – but this is one of the few tracks that I’d take the HD650 over my beloved HD600’s. I get a hint of just a little more contrast again – and for this particular track, it’s captivating.
 
Pop / Rap / Dub / Electronic – tracks tested included:

1. “Turning Tables” – Adele
2. “You Know I’m No Good” – Amy Winehouse
3. “Lose Yourself” – Eminem
4. “Aventine” – Agnes Obel
5. “Electric Daisy Violin” – Lindsay Stirling
6. “Little Man” – Little Dragon
7. “Royals” – Lorde
8. “Tui Dub” – Salmonella Dub
9. “God Is Speaking” - The Flashbulb

 
With female vocals there seems to be more of a contrast between the different headphones, and it’s very dependent on the recording.  With Adele for instance, I loved the contrast of the HD650, yet with the darker recorded “Aventine” from Agnes Obel, there was no competition – HD600 by a considerable margin (for my tastes).  The HD650 with “Aventine” just didn’t have that sweet slightly euphonic tone that I’m used to.  To be fair though – as with all of the comparisons so far, the differences are small, and it’s only by rapid A/B comparisons I’m able to pick up the differences.  For the other tracks – electronic, dub, pure pop – I’m finding that preference is very recording dependent. If the recording is slightly dark, I’m preferring the HD600. If it’s slightly bright, I’m loving the HD650.
 
AMPING / SENSITIVITY
Using the HD650 and HD600 with my LD MKIV OTL tube – both headphones were actually the same on the pot to achieve the same SPL at 1 kHZ.  This was also the same with my X5 – which sounded great with both headphones without adding additional amplification. Preference would be for the LD though as both headphones exhibited a little more bass response.  Not sure if this is the additional voltage or influence of the tubes.
 

CONCLUSION

I came into this exercise thinking that (like last time) I was going to conclude that the HD600 was the better headphone for me, and that the HD650 was too coloured.  Tonight I’ll be packing both headphones for their trip to Auckland – but with a totally different mind-set.
 
I’m not sure if Sennheiser has changed the drivers slightly, or maybe my ears/listening preferences have changed – but I could live with either of these headphones with no problems.  Both have wonderful build, modularity, comfort, versatility – but more importantly sonically they are both “sonic diamonds” for the price.
 
The HD650 is very slightly darker – and although I know the graphs show more bass, it’s not as easily noticeable as the upper-mid / lower-treble differences. The HD600 does appear slightly brighter / airier, and whilst this can definitely help darker recordings, I can’t help admiring the additional contrast the HD650 brings to some tracks when the recording is more neutral or slightly on the bright side.
 
The other thing that has surprised me is how well the HD650 presents the upper end of the frequency.  Cymbals have great detail, guitars still have crunch.  It’s not what I was expecting at all.
 
Will I now sell my HD600 and buy and HD650 – no, I still love the HD600 and when I want a break from the T1 it’s the perfect partner.  Will I now buy an HD650 to compliment the HD600?  No – the differences are too subtle, and both are massively similar than they are different.  But if my HD600s ever fail, and I need to replace them, would I consider the HD650?  Yes – definitely.  If they were priced competitively I would have no qualms switching.
 
As a final note – I’d like to thank my friend Rizki for the loan – and hope he also enjoys his time with my HD600s.  One of these days I’ll persuade him to part with this HD800s for 7-10 days, and then I’ll have a chance to write a T1 vs HD800 comparison.  I can dream …….
 
Thanks for taking the journey with me – I sit now editing it with the HD650’s on my head, Julia & Angus Stone queued, and a smile on my face.

As always, great review Paul! Very nicely & neatly written. It is quite surprising for me to find out the HD600 is too similar to the HD650, as I had originally planned to also get the HD600. Guess I'll find out by myself soon enough how the HD600 sounds with my Senn amp & how close the siblings sounds.

I'll be interested in your thoughts - especially with the HDVA600.  They are both great headphones & thanks again for the opportunity to compare them

No worries mate, the pleasure is all mine as it gave me and everyone else an opportunity to know how they compare from an experienced reviewer's perspective.

great review excellent pictures well done Brooko ....and good on Riski for the loan
When I had both I liked the hd600 the most so kept them..... but now i have a bottlehead crack would like to try again  
all hail the mighty HD600 !  most grovvy headphones    

Great review Brooko. Thanks for your time. I'm about a month into my ownership of the 600's, and just can't get enough of them. I considered the 650's as well, and I imagine I would like them as well, especially after reading this review. The extra $100 ultimately made the decision for me as I couldn't really even afford the $400 that I paid, especially since I bought a Valhalla 2 at the same time. This pairing is really special, and I can't believe the sq I'm getting for less than $800! Its funny that what I consider a huge bargain is thought by everyone else I know to be an insane amount of money for a pair of 'phones and an amp. If only they knew what I would spend if $ were no object.

WOW, very thorough and well made review. Thanks!

Excellent review, thanks  I've had my HD600s for many years and I'm a huge fan.  To my mind, the HD600/650 are the greatest bargain in headphones, full stop. I used to own some early HD800s, and whilst they're clearly a technically more capable headphone, the HD600s just have a magic presentation that makes everything so listenable.  

Excellent review! Thanks!

Mr. Brooko ,
 
Oh my , very nice work here , I admire your completeness .
I too have done similar work in evaluating these devices resulting in the same conclusion but with the earlier version  (HD580)  .  From decades of professional participation in the High-End Audio segment I now conclude the Sennheiser 580/600/650 to be about as good as dynamic transducers can be .  I will mention that I did have a few moments with the HD800 and their matching 800 amp ( at a headphone meet ) and felt the 800 to be a possible improvement on the series .  
  Now , today , I have doubts , arising from a business visit to a Mastering Studio where only superb equipment are selected for daily use and production work .  I discovered amazing performance outputs that make headphones and loudspeakers perform better than my Audiophile pieces . As a music lover and collector I realize that I must have a better Digital Audio converter if I'm to advance and that my previous evaluations were based on lesser sources .  The Antelope DAC and SPL Phonitor 2 combination is breathtaking .   I now feel my lovely Sennheisers are best at making lessor equipment sound good and that they can sound glorious as equipment improves .  
  Sticker Shock is part of this equation , the Antelope/SPL pairing will cost close to $8,000 US !  I'll have to ebay a goodly few pieces from my Audiophile Closet Storage ( unused and maybe not at all loved stuff ) .
 Another difficulty is deciding between the : dcs , MSB or Antelope DACs , the good part is that the Professional Outlets will provide valuable assistance in this matter , the Antelopes are by far the most widely recognized and represented . 
On balance , I mostly value music and own a growing collection of CDs , so my major investment is in Music not equipment .  
There are a growing number of emerging Virtuosos making their first few Studio recordings pressed to CD , not on Major Labels . 
We are living in a time when superb music reproduction equipment & superb musical performances are available , we also can share our discoveries with people on the other side of the World .
Love your work , 
Tony in Michigan 
 
ps. A professional level Digital Audio Converter will have me again doing re-evaluations of my various components , so , I'm holding off on Headphone purchases and judgements , for the moment .  I wonder if I'll have to continue re-evaluations every 5 years or so ? , things keep improving !   

great review!! 
 
ive had similar impressions of both, when i had hd 650, both pairs and others i've heard, ive noticed that they're not as warm and colored as some people say they are, seems to vary alot on amping. but the hd 600 and 650 are certainly very close in sound. i still find the hd 650 to be more colored and darker but its not a huge difference.

Thanks for the kind words everyone.
 
@tonykaz - yes I've wondered often about upgrading my source - and I think it's the next logical thing to do.  Before I do that though, I want to spend some time with an HD800 first. My next actual buying choice is either going to be a pair of HD800s, or a DAC /amp upgrade (eventually thinking Bifrost + Asgard2 + Valhalla 2 - then my H/P rig will be complete).  I can't see me ever moving to the 1K+ per component.  My ears are probably bot good enough to discern any differences anyway. I have to admitat the moment though, the NFB-12 + LD MKIV have never left me thinking I want more with any of my HP - and that includes the T1.
 
@Dubstep Girl - thanks. It was a surprise for me how close the two were.  At times (with some tracks) I even thought that the HD600 might have been the more coloured of the two.  Just goes to show how much of our impressions are also formed by the actual mastering of the tracks we listen to 

brooko said:

 

​

 

INTRODUCTION

Back in January 2014, I wrote a comparison piece on the two Sennheisers I owned at the time (the HD600 and HD700) which proved to be relatively popular read - http://www.head-fi.org/t/725127/comparison-review-a-tale-of-two-sennheisers-hd600-vs-hd700.
 
In that comparison I learnt that I appreciated the HD600’s more neutral and natural presentation over the excitement, edginess, and expansiveness of the HD700. Following the review I was asked a few times how the HD650 would compare to the HD700 (as both were said to have a darker, warmer tonality compared to the HD600).  Unfortunately it was a question I was unable to answer – as the last time I’d heard the HD650 was at least 4 years ago when I was in NY auditioning the HD600 and HD650, and deciding which to buy.  A lot of water has flowed under the proverbial bridge since then – and although I’m not in the position to compare the 650 and 700, I have been lucky enough to borrow a 650 for a couple of weeks.  This gives me a great chance to renew my acquaintance with the HD650, and perform an in depth comparison with my HD600.
 
I’d like to extend hearty thanks to Head-Fi member (and fellow kiwi) 62ohm (Rizki) for parting with his HD650 and allowing me a chance for this comparison.  I of course am going to reciprocate with him once I’ve finished – I know he’s looking forward to trying my HD600’s on his HDVA600.
 
So take a stroll with me on a journey of discovery, and see if my tastes have changed over the last 4 years, and if I’m still happy about the decision I made when I chose the HD600 over its doppelganger – the HD650.
 
ABOUT ME (or a base-line for interpreting my thoughts and bias)
I'm a 47 year old music lover.  I don't say audiophile – I just love my music.  Over the last couple of years, I have slowly changed from cheaper listening set-ups to my current set-up.  I vary my listening from portable (Fiio X5, X1 and iPhone5S) to my desk-top's set-up (PC > coax > NFB-12 > LD MKIV > HP).  I also use a portable set-up at work – either X5 > HP, or PC > Beyer A200p > HP.  My main full sized headphones at the time of writing are the Beyer T1 and Sennheiser HD600.  Most of my portable listening is done with IEMs (I do also have the Beyer T51p, but IEMs command most of my portable time) - and up till now it has mainly been with the Fidue A83 & A81, Dunu DN-1000 and Altone200. A full list of the gear I have owned (past and present is listed in my Head-Fi profile).
 
I have very eclectic music tastes listening to a variety from classical/opera and jazz, to grunge and general rock.   I listen to a lot of blues, jazz, folk music, classic rock, indie and alternative rock.  I am particularly fond of female vocals.  I generally tend toward cans that are relatively neutral/balanced.  I am neither a bass nor treble head (you could argue that I do like clarity though).  I am not treble sensitive (at all), and in the past have really enjoyed headphones like the K701, SR325i, and of course the T1 and  DT880.
 
I have extensively tested myself (abx) and I find aac256 or higher completely transparent.  I do use exclusively redbook 16/44.1 if space is not an issue.  All of my music is legally purchased (mostly CD – the rest FLAC purchased on-line).
 
I tend to be sceptical about audiophile ‘claims’, don’t generally believe in burn-in, and would rather test myself blind on perceived differences.  I am not a ‘golden eared listener’.  I suffer from mild tinnitus, and at 47, my hearing is less than perfect.
 
This is a purely subjective review - my gear, my ears, and my experience.  Please take it all with a grain of salt - especially if it does not match your own experience.
 
I have used the HD600 extensively over the past 4 years (owning it separate 3 times), but this is my first reintroduction to the HD650 for some time, so I may miss some of the intrinsic strengths it brings to the table.
 
REVIEW / COMPARISON RESOURCES
 

​

 

For the purposes of this review and comparison, I used both headphones mostly from my NFB-12 + LD MKIV.  Both headphones were volume level matched using an SPL meter and calibrated (twice) with a constant 1 kHz test tone.  This was rechecked periodically during the comparison.  I used the Little Dot mainly because it was easier to swap with the correct volume matching (more precise markings on the pot).  Tracks used were across a variety of genres – and can be viewed in this list http://www.head-fi.org/a/brookos-test-tracks.
 
PUBLISHED SPECIFICATIONS

	HD600	HD650
Nominal impedance	300 ohm	300 ohm
Weight (no cable)	260 g	260 g
Transducer	Dynamic (open)	Dynamic (open)
Ear coupling	Circumaural	Circumaural
Cable length	3 m	3 m
Termination	3.5mm/6.3mm stereo	6.3mm stereo
Frequency response	12 - 39000 Hz	10 - 39500 Hz
SPL	112 dB at 1 kHz (1 Vrms)	103 dB at 1 kHz (1 Vrms)
THD	≤ 0.1 %	≤ 0.05 %

 
FREQUENCY RESPONSE GRAPH
 

Thanks to Headroom.
 
PACKAGING
 

	[size=12.8000001907349px][/size]
HD650 case left, and HD600 case right​	HD650 left, and HD600 right​

 
Both HD600 and HD650 come in the usual high quality (very large) foam padded hard hinged box, with a printed outer cardboard sleeve.
 
BUILD / COMFORT
 

	[size=12.8000001907349px][/size]
HD650 left, and HD600 right​	HD650 left, and HD600 right​

Both headphones are very virtually identical in build, and I know from my own experience with the HD600, that with proper care, it can last for a decade or more.
 

	[size=12.8000001907349px][/size]
Completely modular build HD650​	Completely modular build HD600​

 
The following applies to both HD600 and HD650.  Both headphones have a moulded hard plastic shell, with steel extenders, velour pads, and soft foam headband padding.  The greatest thing about both the HD600 and HD650 build is that they are completely modular – from the removable cable to the drivers.  This makes it very easy for the owner to replace individual elements – prolonging the headphone’s life.  On my previous HD600, I had already replaced the headband, pads, headband padding, and both drivers – all easily ordered direct from Sennheiser, and fitted myself.
 

	[size=12.8000001907349px][/size]
HD650 screen right and HD600 screen left​	HD650 driver capsule right and HD600 driver capsule left​
[size=inherit][/size]	[size=12.8000001907349px][/size]
HD650 pads and foam cover right and HD600 pads and foam cover left​	HD650 headband assembly right and HD600 headband assembly left​

 
The one weakness in the HD600/HD650 design is the headband itself.  It looks solid, and I read (with my first pair) that it was carbon.  It’s not - it’s molded hard plastic.  New HD600/HD650s are quite clampy.  So I thought the headband would be stronger than it actually is.  So I stretched it – and – SNAP!  OK – my mistake (and an expensive one).  Word to the wise – if you want to relieve the clamp force, fully extend the metal extenders, and bend those only.  You live and learn.
 

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HD650 cable connectors and adaptor ​	HD600 cable and connectors​

 
The major noticeable difference between the two headphones (besides the colour) is the cable.  The HD600 cable is functional – but relatively “light” in build.  The HD650 cable is better built.  There is (to me) no audible sonic difference between the two.  The HD600 also has a plug with built in adaptor, whilst the HD650 plus is a standard 6.3mm.  If I had my preference, I’d like the HD650 cable with the HD600 plug.
 

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HD600 2 piece plug​	HD650 connectors (top) vs HD600 connectors (bottom)​

 
As far as comfort goes – there is no noticeable difference between the HD600 and HD650.  Rizki’s pair of HD650 is a little newer and has a little more clamp – but still remains quite comfortable.
 

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HD650 headband​	HD600 headband​
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HD650 headband padding​	HD600 headband padding​

 
Both the HD600 and HD650 are very light weight, and on both headphones the pads measure (internal space) 7cm x 4cm with a depth of 2.5 cm.  They completely enclose my ears and there are no issues with my ears touching the driver foam.  I can literally wear either pair for hours.
 
SONIC COMPARISONS
 
General frequency summary (supported by graph above):
 

 
 
These were my general notes before actually downloading the graphs from Headroom.  The HD600 to me has always sounded neutralish (maybe a bit flabby in the bass at times), but always a very natural headphone.  I played guitar in my youth, and also attended a lot of concerts.  My mother and grandmother both played the piano.  The HD600 just flat out nails how each of the above mentioned instruments sounds live – no pretensions, no spotlighting – just how the actually sound.  It may not be quite as flat from bass to treble (neutral) as a headphone like the DT880 – but to me it has always sounded a lot more realistic. Because of its tuning – it also has an airy top end without being peaky.  Plenty of detail – without being pushed in your face.
 

 
 
The HD650 (from my memory of it 4 years ago) was similar to the HD600, but darker, bassier, with less air.  The funny thing is that now I have the two in front of me, with my gear, and the ability to volume match, I’m finding those early impressions are not as accurate as I once thought.  For a start, I’m not finding the HD650 dark at all – in fact they seem to be every bit as nimble as the HD600. Tonally they are a fraction short on air, and they also have a fraction more bass – but we’re not talking about big margins here.  The most noticeable difference is that the HD650 just sounds slightly softer – not quite as etched.
 
Soundstage / Imaging:
 
To test soundstage and imaging I’m using Amber Rubarth’s “Tundra” track from the album Tales of The 17th Ward.  The track is binaural – so it gives good queues anyway – but can be very good for a combination of imaging and soundstage width and depth. 
 
Both the HD600 and HD650 display very similar soundstage size – in width and depth and height.  One of the great things I’ve always liked with the HD600 is that whilst the soundstage size isn’t as expansive as AKG’s X701/702 series, or my T1 – it does sound accurate for most music.  As a result  most music I listen to with the Sennheisers sounds incredibly natural – and imaging is definitely not left/center/right – but rather more evenly spaced within the stage.  The HD650 mirrors these same traits, and switching between the two doesn’t change the overall imaging.  Apart from the subtle tonality differences, I could be listening to the same headphones with this test.
 
Switching to Loreena McKennitt’s “Dante’s Prayer” (with the HD650’s in place), and I’m at my usual spot in the audience – around row 2 or 3 back.  Loreena is center stage, and that beautiful cello is sitting slightly back and over to the right.  Again the HD600 and HD650 are too close to tell apart. On this particular track, when the song ends, the applause has always been so natural and enveloping (with the HD600) that I can close my eyes, and for a moment I’m actually in the audience.  The HD650 handles this with aplomb – and I’m there again.  It’s a magic moment – and one that both Sennheisers manage to convey easily.
 
Specific Genre Notes:
 
Rock / Classic Rock / Prog Rock – tracks tested included:

1. “Away from the Sun” – 3 Doors Down
2. “Art for Art’s Sake” – 10CC
3. “The Diary of Jane” – Breaking Benjamin
4. “Hotel California” – The Eagles
5. “Sultans of Swing” – Dire Straits
6. “Boulevard of Broken Dreams” – Green Day
7. “Elderly Woman Behind The Counter In A Small Town” – Pearl Jam
8. “Immortality” – Seether (unplugged)
9. “Money” – Pink Floyd
10. “Trains” – Porcupine Tree

 
The differences are extremely subtle, and more than once tonight, I’ve forgotten which headphone I’ve had on my head.  After a couple of minutes listening (once my ears have adjusted), it’s just not that easy to pick.  But with rapid switching a pattern is emerging, and it seems to be relatively consistent.
 
With the male vocals in particular, the HD650’s have a slightly deeper, slightly softer, and slightly smoother presentation.  It’s not that the HD600’s are grainy either – it’s just that they do have a slightly airier presentation.  I wonder if this is where the comment that the HD650 are “more refined” comes from”?  If it is – I’m not hearing it so far.  They both show the same level of ability and refinement, and the difference is in the slight tonality contrast.
 
Both seem to struggle slightly with faster music (Diary of Jane), but on the slower tracks, tonally both are very natural, and extremely enjoyable.  Switching to one of my all-time favourite Pearl Jam tracks, and I’m expecting two things – and am subsequently wrong on both.  I’m expecting that Vedders voice will sound deeper and better on the HD650’s, and they are both so close that it’s really had to tell them apart.  Yes the HD650 might be very slightly deeper, but the HD600 conveys the timbre of Vedder’s voice slightly better for my ears.  The second preconception I have is that the HD650 will not show the contrast of cymbals (there is a lot of it in this track) with the vocals – and yet the HD650 delivers in spades.  There is no sign of any veil that I can tell!
 
Verdict – too close to call.
 
Opera / Classical  - tracks tested included:

1. “Nessun Dorma” – Pavarotti
2. “Flower Duet (Lakme)” – Netrebko and Garanca
3. “Moonlight Sonata 1st & 3rd” – Wilhelm Kempf
4. “Op.8, No.1, R.269 "La Primavera" - 1. Allegro” – Anne Sophie Mutter & Trondheim Soloists (Vivaldi’s Four Seasons)
5. “OP 35 1st Movement from Tchaikovsky Violin Concerto in D” – Julia Fischer

 
Once again, the differences are so subtle that it becomes hard  to tell the two apart once they’ve been on my head for longer than 2-3 minutes.
 
Both shine with Pavarotti’s “Nessun Dorma” – and manage to convey the majesty of the master tenor’s voice.  But with Lakme’s “Flower Duet” there is the tiniest of differences.  The HD600 do show a little more air in both Netrebko and Garanca’s vocals – but the HD650 shows the slenderest bit more contrast (darker background – or am I imagining it?).  Either way though I could listen to this track with both headphones.  Coupled with the LD MKIV, the presentation is wonderfully captivating.
 
Moving on to Moonlight Sonata – and both Sennheisers performed with distinction.  My grandmother loved the 1st movement of this sonata and played it often.  She would have loved this recording on either headphone – but maybe the HD650 gets a slight nod for the timbre portrayal.  We’re talking preference here though – as both sound wonderful.  Both also performed extremely well with the Tchaikovsky and Vivaldi pieces, and preference would be again up to the individual.  My preference was for the very slightly airier performance of the HD600 here.
 
Jazz – tracks tested included:

1. “So What” – Miles Davis
2. “Gaucho” – Steely Dan
3. “Safer” – Gabriella Cilmi
4. “Love Me Like A Man” – Diana Krall
5. “Ruins” – Portico Quartet

 
For the first time during testing the tonality of the two headphones was easier to tell apart.  With Miles’ trumpet, the HD600 was a tad strident at louder volumes compared to the HD650 (when listening at lower volumes these differences faded).  Portico Quartet’s “Ruins” was a little dark and broody on the HD650 though – and I personally found the HD600 was the slightly easier listen.
 
Switching over to female vocals and the standout track for both headphones was Gabriella Cilmi’s “Safer”.  I know this is more Pop than Jazz – but her voice simply has that jazz undertone.  Both give wonderful presentations – but this is one of the few tracks that I’d take the HD650 over my beloved HD600’s. I get a hint of just a little more contrast again – and for this particular track, it’s captivating.
 
Pop / Rap / Dub / Electronic – tracks tested included:

1. “Turning Tables” – Adele
2. “You Know I’m No Good” – Amy Winehouse
3. “Lose Yourself” – Eminem
4. “Aventine” – Agnes Obel
5. “Electric Daisy Violin” – Lindsay Stirling
6. “Little Man” – Little Dragon
7. “Royals” – Lorde
8. “Tui Dub” – Salmonella Dub
9. “God Is Speaking” - The Flashbulb

 
With female vocals there seems to be more of a contrast between the different headphones, and it’s very dependent on the recording.  With Adele for instance, I loved the contrast of the HD650, yet with the darker recorded “Aventine” from Agnes Obel, there was no competition – HD600 by a considerable margin (for my tastes).  The HD650 with “Aventine” just didn’t have that sweet slightly euphonic tone that I’m used to.  To be fair though – as with all of the comparisons so far, the differences are small, and it’s only by rapid A/B comparisons I’m able to pick up the differences.  For the other tracks – electronic, dub, pure pop – I’m finding that preference is very recording dependent. If the recording is slightly dark, I’m preferring the HD600. If it’s slightly bright, I’m loving the HD650.
 
AMPING / SENSITIVITY
Using the HD650 and HD600 with my LD MKIV OTL tube – both headphones were actually the same on the pot to achieve the same SPL at 1 kHZ.  This was also the same with my X5 – which sounded great with both headphones without adding additional amplification. Preference would be for the LD though as both headphones exhibited a little more bass response.  Not sure if this is the additional voltage or influence of the tubes.
 

CONCLUSION

I came into this exercise thinking that (like last time) I was going to conclude that the HD600 was the better headphone for me, and that the HD650 was too coloured.  Tonight I’ll be packing both headphones for their trip to Auckland – but with a totally different mind-set.
 
I’m not sure if Sennheiser has changed the drivers slightly, or maybe my ears/listening preferences have changed – but I could live with either of these headphones with no problems.  Both have wonderful build, modularity, comfort, versatility – but more importantly sonically they are both “sonic diamonds” for the price.
 
The HD650 is very slightly darker – and although I know the graphs show more bass, it’s not as easily noticeable as the upper-mid / lower-treble differences. The HD600 does appear slightly brighter / airier, and whilst this can definitely help darker recordings, I can’t help admiring the additional contrast the HD650 brings to some tracks when the recording is more neutral or slightly on the bright side.
 
The other thing that has surprised me is how well the HD650 presents the upper end of the frequency.  Cymbals have great detail, guitars still have crunch.  It’s not what I was expecting at all.
 
Will I now sell my HD600 and buy and HD650 – no, I still love the HD600 and when I want a break from the T1 it’s the perfect partner.  Will I now buy an HD650 to compliment the HD600?  No – the differences are too subtle, and both are massively similar than they are different.  But if my HD600s ever fail, and I need to replace them, would I consider the HD650?  Yes – definitely.  If they were priced competitively I would have no qualms switching.
 
As a final note – I’d like to thank my friend Rizki for the loan – and hope he also enjoys his time with my HD600s.  One of these days I’ll persuade him to part with this HD800s for 7-10 days, and then I’ll have a chance to write a T1 vs HD800 comparison.  I can dream …….
 
Thanks for taking the journey with me – I sit now editing it with the HD650’s on my head, Julia & Angus Stone queued, and a smile on my face.

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Well done i enjoyed reading it.

The 6XX family has quietly changed performance attributes from early versions. I have a mid 90's 600 and another from the late 2K's, subtle, but the later versions are slightly more articulate in the vital middle.

achristilaw said:

  The 6XX family has quietly changed performance attributes from early versions. I have a mid 90's 600 and another from the late 2K's, subtle, but the later versions are slightly more articulate in the vital middle.

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Sounds like something out of Godfather.