[Headmusic]

I run my 7xx's via my ****ty little Fiio E14 and it gives it ample juice to give me tinnitus, I imagine those vales amps should power it no problem.

 

[Il Mercante]

Thanks for the insight head music, I am impressed by it, must be a wonderful sight at night with them glowing and the vu meter running, a nice touch to the listening experience!

 

[dharma]

It's old and repeated discussion about HD6xx vs K7xx...
As ex-owner of HD650 and owner of K701, i would go with... 'middle-way' HD600 (not 650). Once I auditioned HD600 for a week and i liked it more than HD650, which had more 'fun' factor (i.e. 'V' shape sound signature). And, at least for me, K701 is too much 'bright' and 'hyper-active' and not 'naturally relaxed' as older K400 or K500.
Maybe, just maybe, if i had a HD600 (and not 650) i would not changed "older version" for HD800 (actually, now i'm happy for my HD800).

 

[theanti]

"Both headphones need dedicated headphones to get the most out of them"

 

[Faber65]

Preface

I own both these headphones, and they are my two main open back at-home listening headphones. I have done reviews of each of them, and due to requests, I've decided to do a comprehensive comparison review of the two. 


Background of the two headphones

The background and history of the headphones can be found in their respective reviews:

HD650 Review

K7XX Review

But to sum it up, the HD650 debuted in 2003 and was Senn's flagship until the 2009 introduction of the HD800. Within these past 12 years it has gone through some retuning to give it a more lively sound from its initially dark and bassy character. I have the 2014 version. The K7XX, launched in 2014 as a collaboration between AKG and the bulk buying site Massdrop, comes from the K7 family, which originated with the K701, launched in 2006. Both headphones are the most recent models in their respective headphone lines. 


Build quality and form factor


Both headphones are around-ear-open-back dynamic headphones with detachable 3 meter straight cables, both feature predominantly plastic construction, and both have velour ear pads. 

The HD650 has a more conventional look to it with lacquered plastic furniture, a ratchet-adjusting spring steel headband with foam padding and metal ear capsule grills. It feels slightly plasticy but after owning it for some time the build quality feels solid enough, and the facts that the headphone can be disassembled mostly by hand, and spares are available for sale, are big pluses. The pivot for the ear cups can feel a bit loose or delicate, but it hasn't broken or snapped on me. The HD650 like its predecessors is made in Ireland and has hand-matched drivers. The cable is dual channeled, well shielded, thick, and terminates to both ear cups with two pins going to each driver, making it a cinch to convert to balanced. It terminates to a 6.35 mm jack, but comes with a 6.35 to 3.5 mm adaptor cable. 








The K7XX uses the traditional AKG design-albeit unconventional compared to other headphones-with twin-parallel rails forming the headband, earcups that pivot in a ball joint, and an unpadded headband that adjusts via elastic straps. The headband design has been around since the K240 Sextett from 1975, and while it is a proven design, long term durability remains a bit dubious due to the use of a more complicated architecture than the HD650, all-plastic components, and very little modularity and ability to easily replace parts. Nonetheless it still feels made. The K7XX unlike previous siblings is made in China, not Austria. The cable like its predecessors is oxygen-free copper, terminates to a 3.5 mm jack with a screw-on 6.35 mm adaptor. and is terminated via a mini XLR jack to the left side cup. The cable is a little skinny, isn't as supple as the HD650 cable, and the use of a 3 pin, single sided termination to only one cup means a much more difficult balanced conversion than the HD650. 







Neither headphone has the tank-like simplicity of a Beyerdynamic DT48, DT770, DT880 or DT150, but very few headphones do. Nonetheless, I will have to give the advantage to the HD650 in this category. Its ease of replacing parts, more robust build, and simplicity of converting to balanced makes it a more reliable long term use headphone. The identically-made HD580 Precision I owned was basically the older sibling to the HD650, and despite being well over 10 years old, was in great working order. If the longterm durability of the HD650's older sibling was anything to go by, the 650 should prove to be a reliable and sturdy headphone for years to come. 


Comfort


The HD650 is renowned for its high clamping force due to the use of spring steel in its headband. The velour pads are stiffly spring and are hard right out of the box. Eventually the pads will soften up, and the clamp will lessen somewhat, but it never goes away; it still remains a cozy fit. The ear cups are tilted slightly back to accommodate the backwards canting of many peoples' ears and the pad openings are elliptical. This presents an issue because due to the high clamping force, the already somewhat shallow pads can collapse under the pressure, causing my ears to press against the foam driver covers and leading to itchiness and discomfort. To remedy this, I stretch out the metal headband section and pivot the left cup forward so it fits over my ear at an angle. This gives just enough extra space in the ear cup to be comfortable, though on hotter days the HD650 can make my ears stuffy. The headband is cloth covered on the inside and has plenty of cushioning. Headband comfort has never been an issue for me. 




The K7XX is a remarkably comfortable headphone for someone like me with sensitive ears. The pads while not massive in their circular opening diameter are big enough for my ears to tuck inside. The cups are deeper, giving enough space so my ears do not press against the drivers. The pad stuffing is a big improvement over the K702 and K701, with a gel-like memory foam that retains its shape, while conforming perfectly to my head shape with no break in needed. It may feel a little hard at first, but it quickly settles in and becomes seamless. The lighter clamping force than the HD650 is a big plus in keeping these headphones comfortable for hours of wearing. While the leather headband does not have much padding, its smooth underside, pliability, and elastic tensioning all allow it to distribute pressure evenly across my hear, creating a sort of upside down "head hammock". 




While the HD650 still remains a comfortable headphone to wear, the advantage in my opinion goes to the K7XX due to its roomier ear cups and lighter clamp.


Sound Quality


Both headphones are situated comfortably in the mid-fi/mid-tier hifi category, and both have a warmish sound to them relative to neutral. However, there are some marked differences. The HD650 an audiophile open back with consumer-friendly sound, and the K7XX an analytical headphone with a little extra warmth. 


Treble

The HD650 has been called a dark or veiled headphone, and while this might have applied to earlier versions, nowadays with headphones becoming increasingly darker, the HD650 in my opinion is not as dark as it is warmish and sweet with a treble that is not recessed but well behaved and well suited to most recordings that are already brightly mastered and sibilant. Brightness is all relative, but in this day in age with music that is increasingly bright and headphones that are increasing dark, the HD650 strikes an excellent balance. There is good extension to the upper treble, but not in an airy or sparkly fashion. The mid treble is well behaved with sibilances that don't break past the acceptability barrier. There is some grain or a bit of haze in the lower treble, but this is mostly due to a little extra energy in this region that adds a level of sweetness to women singers and brass instruments. 

The K7XX while close does have a few differences. The treble has a little more extension, and while the HD650 is sweet, the K7XX is sparkly or a little more fizzy. It isn't what I would call a bright headphone, but it has a more revealing nature to it. There is some stored energy in the upper treble that gives more articulation and air. Symbols crash with a bit more flair than with the HD650. The sibilance range does have a couple extra decibels, but this happens more on a lower end amp, or when the K7XX is under-amplified or is playing an exceptionally sibilant track. I'd say it's a more source-revealing sibilance than a colored sibilance. I will discuss how amplification can alter the two later in the article. Unusually for an AKG, the K7XX has less lower treble, giving women vocalists and brass instruments a darker, and less sweet tone than the HD650. 

I'd call this a tie, with the HD650 having more presence and sweetness in its lower treble, and the K7XX having more sparkle and air up top, and having a slightly more source-revealing sibilance range. 


Soundstage

The HD650 has a soundstage that tends to remain on the intimate side, and while it sounds like an open back headphone, its sweeter sound and more rounded bass response tend to give it a more diffused instrument placement, or "3-blob imaging". It has good sense of a 3 dimensional surround sound, but has a more blurred, softer texture to its layering. 

The K7XX while not much more open than the HD650, has a sharper, better defined image to what one hears. There is better layering to the soundstage, and while the volume of space is about the same, the actual definition to it is better. There is a bit more air, which lends the K7XX an advantage with acoustic, orchestral and classical music.

Advantage: K7XX.


Bass

The bass on the HD650 is another characteristic trait, with lots of warmth, especially in the mid bass and upper bass. It isn't artificial sounding like consumer-oriented headphones, but is noticeably warmer sounding than most AKGs and the Beyerdynamic DT880 Pro. The accentuated mid bass gives vocals and mids a full and intimate, filled-in sound. It's something you quickly get used to, and will not find droning or artificial sounding. Timbre-wise it has a slightly wooden-drum-like texture, with the impact feeling strong in the chest. it makes the HD650 fantastic with pop, jazz fusion, RnB, West African and Middle Eastern traditional music, dance and house music, as well as electronica. Where the bass lacks somewhat is the sub bass. The HD650 exhibits that open-back characteristic trait of rolling off in the sub bass, and just not having that tightness or impact compared to a closed back. That makes it slightly unresolving in the low end, and not a very suitable headphone for hip-hop, taiko drumming and drum and bass. 

The K7XX on the other hand has a much quicker, tighter and deeper extending bass in the low end. It has low-end extension that many open backs simply do not have, and has noticeably better energy in the sub bass than the HD650. It rumbles down low when it needs to, but never feels boomy. Where the K7XX comes up short compared to the HD650 is in the mid to upper bass. It's more on the neutral side than the HD650, and while this gives the headphone a cleaner or quicker bass decay, it doesn't have that warm, intimate fill in that the HD650 has on mid-bassy genres. This by no means makes it lean or weak sounding, because it isn't. It still has plenty of thickness. It just won't sound as warm and thumpy with more synthesized music and electronic bass as the HD650 will. It's more analytical and tighter, whereas the HD650 is more bloomy or chesty. The quick bass decay and great extension toward the sub bass do mean that when amplified correctly, the K7XX will have good impact with some forms of drum and bass, well-mastered hip hop and taiko drumming. The quickness also makes it a little better for rock music than the HD650.

Bass is a draw between the K7XX and HD650, as while the HD650 has more mid bass and the K7XX has better low end bass, the two are equally good in different ways.


Mids

I'm elaborating on the mids lastly, because treble and bass make the mids on both headphones.

The HD650 due to its sweetened lower treble and warm, bloomy mid to upper bass has a very intimate and full midrange, with equally good male (lower mid range) and female (upper mid range) vocal presentation. The HD650 to my ears isn't a mids-muffled or a lazy-sounding headphone. It's slightly mid forward compared to the sub bass and upper treble, though not in a grating way. To my ears the HD650 is right where I like it. It's a more captivating midrange, though, so if you want a slightly less warm midrange, then the slightly-flatter-sounding HD600 might be a little better while keeping similar tonality. 

The K7XX is the more analytical sounding of the two, due to its flatter lower treble and upper bass. The K7XX has slightly shallower or a little drier midrange and vocal presentation than the HD650. This gives it a more analytical tone. It might not be quite as warm sounding, but isn't recessed or u/v-shaped. On a scale of midrange prominence, the HD650 would be the comparatively mid-centric headphone, the Beyerdynamic DT990 Pro and Premium 250 ohm models would be mid restrained/u shaped, and the K7XX and HD600 would be the more mid neutral headphones. 

Both headphones have equally good mids, it's just a matter or preference. The HD650 fulfills my laid back and warm headphone craving moods, whereas the K7XX fills the analytical, resolving headphone desires. 


For sound quality, it's a tie. The one clear advantage I would give in one of the four criteria would be soundstage, with the K7XX having better air, layering and imaging. Other than that it's a matter of taste. The HD650 is lush, while the K7XX is analytical.


Amplification:

Both headphones need dedicated headphones to get the most out of them, but their drivability isn't the same. For both headphones I use the Schiit Audio Modi DAC and the Lyr 2 hybrid tube and solid state headphone amplifier with the stock 6BZ7 Canadian tubes. 

The HD650 has a nominal impedance of 300 ohms, but at the 150 Hz range (upper mid bass area), it swings all the way up to 500 ohms. That said, it's a fairly sensitive headphone, so it doesn't necessarily take a hugely powerful headphones amplifier to get a usable sound and volume from it. In a pinch I have driven the HD650 from the headphone jack on my iPhone 5s and 2011 Macbook Pro, and the sound was moderately loud and quality acceptable. The HD650 scales up with better amplification. A dull sounding amplifier and DAC will often suck the bass impact out of the HD650, and an overly brash or forward sounding system will cause harshness. However, the HD650 still retains its sound signature more reliably across a wider variety of amps and DACs, making it easier to amplify and synergize with. As amps go, the HD650 sounds best with warmish and powerful sounding amps that can put out a healthy supply of voltage and current. The Objective 2 will drive the HD650 decently, but it will sound best plugged into a more powerful, more refined sounding amplifier. The OTC Woo Audio WA6 with its transparency and powerful mids and mid bass will make an excellent compliment to the HD650, as will the WA7 Fireflies, and the solid state Violectric HPA-V200 and V181. My Lyr 2 initially was a little dull sounding with its stock tubes, however the tubes have become a little more lively with more burn in. There is plenty of power in low gain, but in high gain it can become too aggressive in the treble and mids. The high impedance makes the HD650 suitable with OTL amps like the Bottlehead Crack, Little Dot MKIII and MKIV, and Woo Audio WA3, however I've been told that the Schiit Audio Valhalla 2 at least with its stock tubes is not a great match with the HD650 due to having sucked out mid bass. 

The K7XX has a 62 ohm impedance that remains constant from the sub bass to the upper treble. Because of the lower impedance, one might think that the K7XX is exceptionally easy to drive and needs a less powerful system than the HD650. Not so however, as the K7XX is more current hungry, and tends to be much more system-dependent than the HD650. The K7XX has a habit of sounding like what it is plugged into. If your source isn't clean or is lacking in power, the K7XX will sound recessed in the mids, weak in the bass, and brittle and sibilant in the treble. In addition, its 62 ohm impedance also means the K7XX does not play well with OTL tube amplifiers such as the ones I previously mentioned. It sounds best on tube amps with coupled transformers (OTC) with extra current, hybrid amplifiers, and solid state amplifiers from Violectric, Burson Audio, and Lehmann Audio (though those tend to be expensive). I find my Lyr 2 to have plenty of current and bass for the K7XX, and it makes for a great synergy, even moreso than the HD650. The Schiit Audio Asgard 2 will make a good pairing for the K7XX if money is a constraint, and the Vali will make a great sub 200 dollar energetic amp. 

It might seem a little strange to rank the two headphones in this category, but due to its higher impedance and higher sensitivity, as well as its ability to better retain its sound signature on different systems, the HD650 is an easier headphone to amplifier and work with on a wider variety of equipment. The ease of running it balanced is another advantage. The K7XX is deceptively challenging to work with, and is pickier with systems due to its more revealing tone and odd low impedance, current hungriness. It also doesn't help that its sound varies noticeably on different systems. The HD650 takes this round. 

And last but not least, Value

The HD650 retails for 400-500 dollars, and is widely available, whereas the K7XX goes for 200 dollars, but is only can be bought on Massdrop and it's limited edition, meaning that once the production ends, no more units for purchase, and if you have a chance to buy it you have to wait for the group buying sale to start. No returns accepted is also a big sting should you not like the K7XX. As resale goes the HD650 has held its value well, whereas the K7XX's residual value will not likely be as good. The 200 dollar purchase price might appear to be a much better value than the HD650, but remember that while the HD650 will sound good on a wider variety of systems, you will likely be paying more money for a system that sounds best with the K7XX, and will likely end up spending as much money as the HD650, if not more. The lower price of AKGs can often be a false economy, as the system that they will work best can often cost twice as much as the actual headphone. The HD650 will sound excellent on a system costing the same or even a little less than the headphone. While the K7XX is much cheaper than the HD650, its system pickiness and limited availability make it a lesser value. The HD650 takes the win in value. 


Conclusion

To wrap up this review, both headphones to me are equally good. For me they are great on my system and compliment one another well. So I'll take both. But for the average person it's going to be a different story. The warmer, more bloomy sound of the HD650 has found more supporters than detractors, and is a no-nonsense and choice and a more reliable option than the K7-series. The fact that the HD650 is less picky than the K7XX on systems and will sound better on more amplifiers makes it much easier to buy an amp and DAC, and be happy with the results. There isn't a bunch of messing around with USB connections, tubes, opamps, amps and DACs to get a great sound. The HD650 is a less fiddly headphone for the average person and much easier to achieve great synergy with. 

[COLOR=FF4400]
[/COLOR]

For me, it's a tie, but for the average person, I am giving the win to the HD650 in this comparison. 

I own both and I use them with different amps (see my profile for the details).
Apart from the good job made in this review by bpandbass, with the only exception of the consideration about the clamping force (I have a small skull as basically it hasn't much to contain and it's only real function it is the spacer for the ears) I found myself in total agreement with his opinions.
Well done Sir.

 

[Faber65]

"Both headphones need dedicated headphones to get the most out of them"

As per my very personal experience, remaining Ina a price range of $200-300, the K7XX has a nice synergy with the Schiit Vali 2, while the Burson Lycan makes the HD650 fast, alive and kicking.

 

[Koolpep]

Having both headphones, I agree as well. Burson Conductor drives them both very well, as does ifi iDSD micro.

Didn't try them on the liquid carbon yet but expect some really sweet sound from there as well....

 

[Faber65]

Having both headphones, I agree as well. Burson Conductor drives them both very well, as does ifi iDSD micro.

Didn't try them on the liquid carbon yet but expect some really sweet sound from there as well....

I did not want to mention the Burson Conductor as maybe it's a little out of budget for many.
From such as top class amp obviously the expectation is to drive well almost all the cans.
So it does.

 

[m8o]

This thread is pretty old and inactive by now. But I have a fairly notable finding in this comparison this past week I thought was worth sharing for anyone coming along interested in this very topic.

I was listening to one of the Carson Daly's with GEM performing (I use optical out of my cable box to a quality DAC feeding my McIntosh MHA100). Was listening to the abbreviated last song on my HE1000. It starts off as ethereal vocals that i had quite loud. Then the incredibly bass heavy music kicks in after a bit. Whow that was unexpected and incredible sounding; that I'm using the speaker taps with them certainly maximized the dynamics and negates any 'softness' folks attribute to the HE1K.

So I think, let me try this out with a lot of my headphones. So long story short, skipping over everything but this threads subjects...

- I try it out on the hd650; high gain, 150-600 ohm impedance selected on the autoformers.. when the highly impactful music comes in, the meters peak well above 5 watts. I'm pretty impressed how well it handles the dynamics. Bass slam is there, all frequencies are clean and clear, and only the ever so slightest bit of compression on the bass handling the dynamics & slam when the music starts in comparison to what the HE1K could deliver. I'm quite impressed and am reminded of how deserving the HD650 is of headtime; which it rarely gets now that I have the Ether, HE1000, and now TH-X00 (really liking that). I am definitely going to give the HD650 more love.

- I do the same on the M7XX; 50-150 ohm autoformer tap. And I was completely shocked; in a bad way. When the highly impactful music started the M7XX completely fell apart into distortion. It wasn't even that loud; and it was compressing heavily too. I know this HP is lite in its power handling rating. But I was still surprised when I witnessed that 1st hand.

I have a AntLion ModMic 4.0 on it now and use it as a headset for work as its so incredibly comfy; I have to use a headset for many hours at a time as I'm part of a global development group that collaborates often. It replaced a Beyer on ear and has been great for that; just wish it traveled better.

But for me, the HD650 and M7XX are in totally different categories. The M7XX can play with it at low volume/power. But the HD650 is capable of so much higher power handling producing so much more clean music dynamic range it really surprised me.

 

[objectionform]

Thanks so much for this thread and all of the follow-up comparisons.  Just started diving into this new obsession, as I've been satisfied for the most part with my DT880's and my O2 DAC/Amp.  After vacillating between the K7xx's and Senn 600's, I was all set to pull the trigger on the Senn's before noticing that the K7xx's were back up on MD.  As I like my bass to rumble (cleanly), for the price I finally pulled the trigger on the Chinese K7xx's.
 
I have no doubt I'll grab a pair of Senn's in the future, since a massive amount of people claim they are great "reference" headphones against which others should be measured, but I'm extremely excited about the K7xx's.  Many thanks about the tips on burn-in.
 
Next stop - a Schiit stack and dreaming of Audeze LCD-X's!

 

[Captain Morgan]

I've owned the Sennheiser HD650 for a couple of years now, and I still love it like a little newborn German baby. I also own the K7XX, and for $200 it's really hard to beat. It's the most comfortable headphone I've ever used. It's like if your ears were lying naked on a shag rug! Ooooh, that memory foam!
 

 

[Gfresh404]

delete

 

[Gfresh404]

Having both headphones, I agree as well. Burson Conductor drives them both very well, as does ifi iDSD micro.

Didn't try them on the liquid carbon yet but expect some really sweet sound from there as well....

 
Just wanted to clarify, the iFi Micro DSD does in fact pair well with the AKG KXX? I already own the iFi Micro and am thinking about picking up a pair of the AKG KXX's

 

[Koolpep]

   
Just wanted to clarify, the iFi Micro DSD does in fact pair well with the AKG KXX? I already own the iFi Micro and am thinking about picking up a pair of the AKG KXX's

 
Hmm, can't remember. I will try tonight, when I am back home.
 
Cheers.

 

[Koolpep]

   
Just wanted to clarify, the iFi Micro DSD does in fact pair well with the AKG KXX? I already own the iFi Micro and am thinking about picking up a pair of the AKG KXX's

Just tried the K7XX with the Burson and the iDSD micro and the iDSD drives it very well and I think it pairs lovely with it. Very musical a bit warm, liquid and full bodied.
 
cheers.