Comparative review of the AKG K501 and Sennheiser HD600 headphones (long!!)

[Don Quichotte]

Comparative review of the AKG K501 and Sennheiser HD600 headphones without a dedicated headphone amp (and with stock cable). Burned in headphones and very diverse partnering equipment; based on 3 months experience.

Although I called it so, this is not a complete review, I think that would be redundant considering the great number of posts debating the pros and cons of these two phones and often comparing them with regard to bass, transparence, soundstage, etc. Rather, I am trying to highlight some aspects of the phones that seem to me to have escaped to most other reviewers, or at least didn’t receive enough attention. Also, some comments I’ve read here on Head-Fi or on Headwize seem contradictory, so maybe I could be of some help. I want to mention (and this is VERY important) that, being quite sure about what I’ve heard, I am also very aware that using these headphones without a dedicated amp is said to be totally non-recommendable. For me, purchasing an amp in the next future is out of question for financial reasons and on the other hand the headphones choice is very limited in my country, so I may be excused for this rude behavior. I never had the chance to audition a headphone amp, but I realize from the tons of descriptions on this site that some of the shortcomings I’ve noticed at the AKGs and Senns could be at least alleviated by using them with an amp; still, I've got the feeling that even then the differences between them would remain more or less the same. If you believe that the differences I described here are not the ones you heard using amps, say so, for the sake of all the dead heroes on the battlefield in the AKG - Sennheiser war...

Then why this review at all, you may ask? Because I’ve heard these phones in quite a few different setups, including out of the headphone jack of several mid-fi or good integrated amps (a top of the line Sony, a Marantz PM 17, etc.) and a professional mixing table, and all the differences I’m mentioning here were maintained (if both phones improved, it was to a similar degree, so the differences remained more or less the same). Moreover (and this is where I would be very glad to take advantage of your experiences, guys) I am hoping and I am inviting you to come with some comments about my statements here. Please validate (or invalidate) my impressions, making this a good source of information for anyone who may be in doubt about choosing between these two headphones even if intending to use them with an appropriate amp. Maybe someone who is really concerned with instrumental separation, for example, could be warned about a possible deficiency of the K501 in this regard, at least by comparison with the HD600, write a post asking for clarifications and you could tell him/her more.

One last warning: I am trying to account for some differences focusing on qualitative descriptions that may make the characteristics I am talking about appear as very pronounced. Sometimes these characteristics are striking (for my ears, at least), sometimes they could go unnoticed. Don’t assume that calling the HD600’s sound “electric” I mean that they sound electric compared to my idea of how a “natural” sound could be or to the live music; I only mean that compared to the K501.

So, taking all these into account as well as the subjective nature of my impressions (obviously!), those of you who haven’t got bored yet please read, agree or disagree, but share your comments.

General tonal behavior and midrange: both phones are colored, but in very different directions. Beside the mid-bass bump and the recessed midrange as a whole, the HD600 seem to have a dip somewhere in the middle of their medium range. I noticed this especially on piano recordings, that sounded like that piano would have had only lows and highs, any note seemed to belong to the highs or to the lows or to both departments at the same time, but never mainly to a “medium range” on its own (once again, this is only by comparison to the K501, in objective terms this description is very exaggerate; of course you are hearing midrange notes on the HD600). The piano sounds more “fleshy” (especially complex accords played forte sound delightful) and more coherent on the K501, as if it really were a single instrument. K501 suggests me a full range driver, while HD600 sounds like a more potent 2-way loudspeaker with excellent drivers that messes things up somewhere in the middle with its bad implemented crossover. The piano on the HD600 has both more weight and more sparkle, but still sounds farther away from reality by comparison. Generally, the HD600 is more colored than reality, addictively romantic (on flute for ex.), but also sometimes sounding a bit “electric”. This coloration made me think that these headphones are best suited for electronic music like Jarre as there is no problem to color a bit the sound of a synthesizer – you’ll only get a different, but not less “natural” synthesizer sound. On the contrary, the K501 are less colored than reality, de-colored if I may say so, which partly accounts for their unfatiguing sound but also for a more “papery” and drier sound (by contrast to HD600’s “wetter” sound). Some say it’s too obvious you are listening to a recording, you simply can’t get fooled into thinking this is live sound (sometimes it’s true), while others complain of boredom (but I totally disagree; see my comments about musicality). They (the phones, not the people) seem to mate well with livelier, more colorful recordings like closely miked acoustic instruments. Eric Clapton’s “Unplugged” is a good example (but it’s a bit too lively and I find it tiring after a while). And yes, as somebody else has already noticed by comparison to K1000, HD600 seems to decrease the pitch of the voices (and other midrange timbers, but on the voices it’s most obvious) almost an octave compared to K501 – or maybe AKG headphones are the least realistic; two obvious examples are Tracy Chapman and Willie Nelson. This illusion is of course given by these phones’ very different equalization, not by a faulty pitch reproduction.

Highs: A minor shortcoming of the HD600 is the subtle presence of a kind of high frequency “white noise” accompanying cymbals and triangles, not like a different sound or an echo, just like a coloration or smearing of the sound that otherwise would have had outstanding detail. The K501 have much more subdued highs, which I find particularly unpleasant on piano or some cymbals, but fares better on triangle (that sounds more natural that on the HD600) and on trumpet because of the sharp sound of this instrument. If quantity wouldn’t be an issue, I think K501 would be better at this department, but I preferred the HD600 a bit with regard to treble reproduction. I disagree with those who praise the K501’s highs (they are excellent in the same way as the bass, i.e. strictly qualitatively, while in quantity – and extension, at the low end – they are quite deficient); also, I really don’t find the HD600’s highs subdued at all, rather the opposite.

Lows: Just like the highs, the K501 would reproduce the lows better that the HD600 if it weren’t for the quantity of bass (medium is quite diminished and low bass almost non-existent out of K501). What do I mean? Bass is really tight and fast on K501, very tuneful, very textured... the one that exists. The plucked strings of the double bass in a jazz group sound realistic (except for the lowest notes), while the big drums in a group like Dead Can Dance are cavernous (albeit light, if you can understand such a combination of attributes). The bass is not intruding on the mids, it doesn’t “contaminate” the lower midrange with any coloration, which I appreciate very much. The HD600’s bass is quite the opposite: very deep, warm, weighty, slower and uncontrolled by comparison and simply there’s too much of it. It’s a pleasure to hear such a ponderous bottom end when listening to some Bach organ works, but for example on “Portrait of a Romantic”, the first track of John Surman’s superb “Private City” album (ECM, 1988), the mid-bass synthesizer notes at the beginning are too strong compared to the (otherwise beautiful, liquid, romantic indeed) laid-back bass clarinet and tenor saxophone.

Spatial presentation: This is an area where most say that K501 excels. It excels indeed when it comes to soundstage width: it’s incredible, and I’m in love with it. I never found myself thinking “boy, this is unnaturally large on this track”, “it’s too wide for rock” or anything like this, never. There’s so much air, and so much light! Unfortunately, while obviously wider, its soundstage is also obviously less deep than the HD600’s, and also somehow less integrated. What I mean by “less integrated” is that, by comparison, the K501 sounds more compartimented in three departments: left, center and right. Also, the placement of the various instruments on this stage is more clearly delineated by HD600. On Vangelis’ “Direct” album, on the first track there’s a synthesizer sound traveling anti-clockwise in a circle or an ellipse, and its route was easier, more effortlessly distinguishable out of the HD600 than out of the K501. Generally, on the K501 the instruments appear as larger and with less clearly delineated edges, filling its (greater) soundstage, as more and more instruments come into play, sooner than on the HD600. For me this is the main asset of HD600 over K501 for symphonic music (overall I think they are equally good for symphonic).

Detail: Now it gets really interesting. Detail means differentiation, a contrast or clear delineation between something and something else. Now, chromatic contrasts are a just a little bit more pronounced on HD600 (I’m talking about the color/flavor/timbre of this sound/instrument compared to that one, not about the pitch); Bartok’s “Concerto for Orchestra” Sz 116 interpreted by Berliner Philharmoniker / Sergiu Celibidache (EMI Records) somehow lost a part of its magic when moving from HD600 to K501 precisely because of this (but this cannot be generalized to all the symphonic music, the recording itself matters a lot – 20-30 years old Deutsche Gramophon recordings with Karajan, for example, sound at least as good on K501 as on HD600). Spatial contrasts are generally more obvious on HD600 (when it comes to small “distances” between instruments or to distances in depth; of course that the extreme right and extreme left of the K501 are more contrasting one to each other than those of HD600). HD600 also have faster transient response, and on Vangelis’ “China” for example it was easier to distinguish the many different sounds, you were hearing them without “trying”; on K501 it was all there, but discerning all these sounds required more effort. K501 puts the solistic instrument forward, charms you with its open and detailed presentation, but somehow overshadowing the other instruments and making more difficult to perceive them as a whole group with interrelated musical lines. Someone has explained an apparently similar behavior (huge soundstage and the same highlighting of the solistic instrument as opposed to a more blurred background – I’m talking about Stax Omega 1 compared to Omega 2) by the more emphasized midrange. I think it’s quite plausible. Anyway, this is why I feel that K501 are best suitable to small and medium size jazz groups, string quartets, generally acoustic music with no more than, say, 6 or 7 instruments (or solo instruments – classical guitar sounds gorgeous).

But now I would like to point to 2 detail-related aspects that I perceived and that I haven’t found mentioned anywhere else; I might be wrong, so I need your feedback on these. First, sometimes I got the feeling that K501 doesn’t reproduce the pitch as clearly as HD600. On any of the Paco de Lucia / Al Di Meola / John McLaughlin albums it was easier to follow the melodic lines of the three frenetic guitars on HD600 not only because of its slightly superior speed (in midrange and treble), but also because it was easier to say exactly what note is being played by each guitar at each moment. If I were able to write down the notes of a complex musical work only by listening it, HD600 would be a more revealing tool to use than K501. Frankly, I don’t understand this phenomenon, it might be related to the K501 dryness. Second, K501 does a much better job in reproducing easily and convincingly the tiniest, most subtle nuances of intensity (I’m not talking about the deep bass, of course, it’s mainly in the midrange where this is apparent). This makes it sound more dynamic than HD600, more passionate. A sudden orchestral fortissimo can sound frightening, not as weighty as on HD600, but subjectively perceived as “more sudden”, if I may say so, and more convincing. Kari Bremnes’ voice on her wonderful “Norwegian Mood” album, or Patricia Barber’s voice, if you are more familiar with her, are presented with all their inflections, all their emotion, to the tiniest details of their softest whispers. I believe K501 shares this quality with K1000, judging by some reviews that described K1000 as more dynamic than HD600, but I’m not absolutely sure if they meant what I described above.

Impact / substance: As I said before, HD600 has more weight, while K501 has better dynamic contrasts. Also, K501 is able to give the instruments a more consistent substance in my opinion, a solo saxophone for example can fill your ear with its sound, whereas on HD600 it remains more in reserve, perhaps sharper focused but less willing to come wholeheartedly to you. All kinds of percussion have a faster and more precise attack on HD600, but sound overall better on K501 (to my ears) because of this sense of solid substance.

Melodicity: In the end it all comes down to this, doesn’t it? The problem is that the ability of a headphone to communicate the music to us depends very much not only on the headphone performance, but also on our subjective weighting of this or that trait. For me, the realistic dynamics could be very important if I am to be completely immersed into music and to fully participate to its emotionality; for you, spatial presentation could be more important. I had to chose between these two headphones after several months of intensive auditioning, and it was really, really difficult. HD600 is a very polished and very capable headphone, with a smooth, mellifluous, warm yet detailed and extended sound, and is able to present the musical relations between instruments (spatial, timbral and tonal relations) better than K501. Some very obvious, easy to remark strong points. The K501’s assets are less obvious, this sounds like a less pretentious headphone (and more forgiving with the bad records, I would say). However, for my ears it has a tremendous melodicity coming from its exquisite, passionate rendering of all the shades of intensity, its substance, its overall coherent, tightly controlled sound from top to bottom, forthright and full of emotion – all this taking place in an immense, airy and relaxing soundstage. You need some time before you start to appreciate its more subtle qualities (except for the soundstage, which could hardly go unnoticed) and to forgive its somewhat weaker top and especially bottom end, but once you get used to its sonic signature you’ll find the K501 a very rewarding headphone indeed. In the end I decided that K501 stays and HD600 goes, but I would rank them as equally good and highly complementary headphones.

That’s it! Hope I managed well enough with English...
Comments?!

[ooheadsoo]

Very insightful review! I greatly appreciate your time and effort put into this!

Now if only I had the money to spend on testing a pair of these out....

[shivohum]

This was a pleasure to read, Don! Thanks.

[Val]

First of all, your command of English is impressive and I should know because it is also a second language for me. God knows I have struggled with it for years.

This is a classic, never-ending headphone comparison and I agree with your general findings. Comments:

1. I don't know if the lack of a headphone amp is necessarily fair in this case; my guess is that it favors the HD600 if only because the K501 really needs an amp to sound more powerful (especially in the bass) and free of any shackles. A good amp like the Kordas (the HA-2 is my next purchase) with an aftermarket power cord like the Ambiance PowerChord does wonders for the AKG. I don't think the Sennheiser would benefit as much.

2. They are almost exactly opposite in bass measurements; the AKG slowly drops off starting at midbass, the Sennheiser exaggerates bass almost by the same amount and in the same range.

3. I also find the HD600's midrange recessed and its treble just a bit sharp; I also think that the K501 is very neutral (almost as neutral as the ER-4S) but a bit dry sounding.

4. I think that for most people and as a first impression, the HD600's extra bass and treble help it in a direct comparison with a more neutral headphone like the K501, but I find the AKG general liveliness more to my liking than the Sennheiser's enhanced frequency extremes and recessed mids.

Val

[darcangelo]

the Sennheiser's enhanced frequency extremes and recessed mids.

huh??? from the reviews I've seen, I always got the impression it was the other way around: strong mids and "edged-off" extremes. What gives??

SMI²LE

[tanfenton]

Your review, more of an essay as I've read it, compelled me from its opening to its closing. Thoroughly and with great respect to both headphones, you penned prose I find very fitting of the HD-600, and, in your communication of the K-501, an even better picture than you might be aware of the K-1000. So I urge you to try it, as a natural extension of thought, and distill your experience as you've done so beautifully here.

NGF

[Beagle]

The bass is not intruding on the mids, it doesn’t “contaminate” the lower midrange with any coloration, which I appreciate very much

An excellent description of the 501 bass. Wonderfully thorough enlightening review.

Of course you are going to get a few rebuttals saying it was an unfair test because you didn't use a dedicated headphone amp, but your findings are the same as mine for the most part..

[joelongwood]

WOW! That, my friend, was one of the most wonderfully written reviews I've had the pleasure of reading. I've been listening the past few days to the AKG K501s with the RKV amp, which is known to provide adequate power for the 501s, along with excellent bass, and the pairing is very synergistic. I really like these 'phones.
Thanks so much for your insights into these two excellent headphones.

[Monica]

I love my K501. Even straight from my portable, they sound good. Of course, a better amp will make them sound better. I reach for them more often than my AT’s that cost several times the K501. I am not sure why because I can make a list of things that other cans are supposed to do better.

[NEO]

How is the bass level from AKG-K501,especially compared with Grado SR80?
NEO

[Don Quichotte]

Thanks a lot for the nice words. As far as hi-fi is concerned, chosing between these two phones has been the strugle of my life! Some day I'll buy again the HD600, some replacement cable, the K1000 of course, one or two amps, a good source, maybe some Magnepans......... Should I dare mentioning some electrostatics also?...
Well, maybe not really all of them in the same day.

"huh??? from the reviews I've seen, I always got the impression it was the other way around: strong mids and "edged-off" extremes. What gives??"
No, it's the other way around. Probably your impressions are based on praises with regard to HD600's smooth and detailed midrange, but also remember I didn't use either a dedicated amp or a replacement cable. Tubed amps and the Cardas cable are said to enhance the mids, if I got it correctly.

Sorry NEO, I have no experience with Grado phones...


For now, I've got a few questions:

"I've been listening the past few days to the AKG K501s with the RKV amp, which is known to provide adequate power for the 501s, along with excellent bass, and the pairing is very synergistic."
Joelongwood, isn't this combination seriously defficient in treble?

"...in your communication of the K-501, an even better picture than you might be aware of the K-1000. So I urge you to try it, as a natural extension of thought, and distill your experience as you've done so beautifully here."
Aren't the K1000's highs more pronounced than the rest of the spectrum, even a bit metallic? How good are its highs, really?
Yes, I will try (misspelled: BUY) them, but not very soon.

What do you all think of my comments regarding spatial positioning and intensity and pitch reproduction through K501? I am really interested if these traits are maintained even when using a good headphone amp. Also, how good / how much better are K1000 in these regards?

Thanks again!

[KR...]

If there is any headphone that benefits more more a high powered amp than the AKG 501, I can't name it. The AKG when pair with a amp like the Headroom Maxed out Home they sound like a totally different phone than a 501 when matched with an amp that doesn't put out as much power. The difference is truly night and day.

[jopi]

Originally posted by Don Quichotte
Aren't the K1000's highs more pronounced than the rest of the spectrum, even a bit metallic? How good are its highs, really?

Thanks for your original posting, I've enjoyed it.

It seems, that we've got similar preferences when it comes to headphones. I've also decided to keep the 501s and sell the HD600, not because they're better headphones, but because they had advantages over the HD600 in areas that matters most to me.

I've also have the K1000 for about 9 mine month and a good amp along with it for about 3 month. For a full review check out my post in the amp review section.
I find the K1000s shares some of the characteristics of the 501s. Bass extension is not as deep as HD600, but I think more accurate and visceral. I'm not sure about the highs yet, the K1000 bring out more detail and I may confuse more detail with better high end extension, so the verdict is still out on that one.

KR... posted, that an amp changed the sound of his 501s like night and day. I've had similar experience, but not quite as drastic.
The results are indeed that dramatic with the K1000. My K1000 sounded metallic and shrill with my home theater solid state amps. I almost never listened to them using this setup.
With my current tube amp, I can't stick any sonic signature to them and I almost never listen to the 501s now.

To sum it up: The K1000 are similar to the 501s, but more in almost all areas. They provide more detail, reach down lower, provide speaker like visceral bass and gobble up even more power than the already power hungry 501s.

[joelongwood]

"I've been listening the past few days to the AKG K501s with the RKV amp, which is known to provide adequate power for the 501s, along with excellent bass, and the pairing is very synergistic."
Joelongwood, isn't this combination seriously defficient in treble?

I wouldn't call it "seriously" deficient at all. Yes, there is a slight (to my ears) roll off of the high frequencies, but the depth and taughtness of the bass is what impresses me most about this combo. The midrange is incredible.It's a very full, rich sound......better than I've ever heard from the K501s.

[elrod-tom]

Excellent review!! Oh, and let me be the first to extend an invitation to join Team AKG!!