Dan Clark Stealth Review (State of the Art Headphone)

[ifloatoveryou]

Your criticism assumes I have some magical ears that give you the truth that way. I do not. I am far more reliable looking at measurements to see if they have audible impact as they seem to indicate, or not.

I did not mean to suggest that you have, or could have, golden ears that are more reliable than measurements in evaluating headphones. Amir, I think your science based approach is excellent and I like your reviews.

I also did not mean to suggest that your subjective impressions are more flawed than other reviewers' subjective assessments because they listen first, or that your subjective impressions would become more reliable if you simply listened without measuring. I think you should listen before and after characterizing the flaws in the measurements and by not doing so you subject your subjective impressions to unnecessary bias.

Subjective listening is much less important than measurements. Verifying your analysis of measurements and assessing the impact of any of the measurement's flaws however is still a somewhat important part of the review, even if inherently unreliable. Like any subjective assessment, not just in the world of audio, yours is subject to bias. In general, humans are biased to like to affirm their beliefs - this is science as well. I am suggesting that: you would be less susceptible to this bias of wanting to confirm that you hear the flaws you noticed in you analysis, if you listen before and after characterizing flaws in the measurement, as opposed to just after. This is less relevant for tonality, such as not enough sub-bass, and more relevant for other perceived flaws in the frequency response, such as a lack of smoothness.

Whether or not this is feasible without potentially biasing the measurements is a different question. Hopefully this clarifies my criticism and why I am making this suggestion.

 

[solderdude]

In general, humans are biased to like to affirm their beliefs

I wonder how many people have been adjusting EQ sliders somewhat and thinking it sounds better only to find out that the EQ was not enabled/bypassed. It's so easy to hear changes when one thinks they are doing just that even when nothing changed in reality.

 

[Thomas_A]

I did not mean to suggest that you have, or could have, golden ears that are more reliable than measurements in evaluating headphones. Amir, I think your science based approach is excellent and I like your reviews.

I also did not mean to suggest that your subjective impressions are more flawed than other reviewers' subjective assessments because they listen first, or that your subjective impressions would become more reliable if you simply listened without measuring. I think you should listen before and after characterizing the flaws in the measurements and by not doing so you subject your subjective impressions to unnecessary bias.

Subjective listening is much less important than measurements. Verifying your analysis of measurements and assessing the impact of any of the measurement's flaws however is still a somewhat important part of the review, even if inherently unreliable. Like any subjective assessment, not just in the world of audio, yours is subject to bias. In general, humans are biased to like to affirm their beliefs - this is science as well. I am suggesting that: you would be less susceptible to this bias of wanting to confirm that you hear the flaws you noticed in you analysis, if you listen before and after characterizing flaws in the measurement, as opposed to just after. This is less relevant for tonality, such as not enough sub-bass, and more relevant for other perceived flaws in the frequency response, such as a lack of smoothness.

Whether or not this is feasible without potentially biasing the measurements is a different question. Hopefully this clarifies my criticism and why I am making this suggestion.

In my limited experience evaluating headphones without prior knowledge of measurements, you really need tp be able to AB the headphones against each other. While crap headphones reveal themselves quite fast, others need a more iterative listening to grade them.

 

[solderdude]

It also helps to have a reference (either speakers or headphones) to compare to and to 'reset' the hearing. At least that helps for me.

 

[EJH]

Subjective listening is much less important than measurements.

Both are important. For instance, Ananda and Koss 95X measured poorly and got relatively bad reviews from Amir, while he gave the HD650 a thumbs up. Well, I owned the 650 for two years and tried over and over again to like it. Never did. That headphone left me cold. I found it atrocious for orchestral music, which is what I mostly listen to. Even for rock and pop, I always felt like there was a thin layer of ice between me and the music. They also sounded kind of dark. Meanwhile, I currently own the Ananda and 95X and like them both so much better. That they measured worse than the 650 makes no difference to me. I’m not suddenly going to like the 650 and dislike the other two because of measurements. While I find measurements interesting, when it comes to headphones, I take measurements with a grain of salt. Objectivity is not enough.

 

[ifloatoveryou]

Both are important. For instance, Ananda and Koss 95X measured poorly and got relatively bad reviews from Amir, while he gave the HD650 a thumbs up. Well, I owned the 650 for two years and tried over and over again to like it. Never did. That headphone left me cold. I found it atrocious for orchestral music, which is what I mostly listen to. Even for rock and pop, I always felt like there was a thin layer of ice between me and the music. They also sounded kind of dark. Meanwhile, I currently own the Ananda and 95X and like them both so much better. That they measured worse than the 650 makes no difference to me. I’m not suddenly going to like the 650 and dislike the other two because of measurements. While I find measurements interesting, when it comes to headphones, I take measurements with a grain of salt. Objectivity is not enough.

I would recommend you watch Amir's video he posted last page, it goes into detail regarding measurements' importance.

I do not think subjective assessments such as sounding kind of dark or having a layer of ice between you and the music are meaningful. It is okay to say these things, this review for example describes the hearing the stealth for the first time like seeing an OLED screen for the first time. These subjective analyses however tend to be nonsense. I don't mean this an assessment of your or Amir's particular subjective claims, but instead a general statement.

When I said subjective assessment in my previous post, I am strictly referring to characterizing flaws of and verifying analysis of measurements. This is a subjective activity and it unfortunately has a chance of being nonsense. I think Amir could do this subjective activity more reliably if he listened to the headphones both before and after analyzing measurements. In particular I think using the stealth as a reference to AB the headphones when listening prior to analyzing measurements would be good practice.

Another term to refer to characterizing flaws of and verifying analysis of measurements besides 'subjective assessment' would be useful, as it is very different than describing a headphone as having a layer of ice or comparing a headphone to an OLED tv.

 

[amirm]

I wonder how many people have been adjusting EQ sliders somewhat and thinking it sounds better only to find out that the EQ was not enabled/bypassed.

As I create and play with EQ with every speaker and headphone review, this and its variation has happened at least 20 times. Last time was a common one with EQ being on from a different unit when I first listened to the headphone. I immediately though, "hmmm, this can't be right -- measurements showed differently." Checked and found the issue. This has been the case *every* time fortunately. I run into the case you are talking about as well and at first I may be fooled but quickly realize it is not making a difference because the whole EQ setting is off.

That said, yes, I suspect it does happen to people.

 

[amirm]

When I said subjective assessment in my previous post, I am strictly referring to characterizing flaws of and verifying analysis of measurements. This is a subjective activity and it unfortunately has a chance of being nonsense. I think Amir could do this subjective activity more reliably if he listened to the headphones both before and after analyzing measurements. In particular I think using the stealth as a reference to AB the headphones when listening prior to analyzing measurements would be good practice.

Let me make sure I point this out as I have mentioned it a number of times: I do NOT memorize the frequency response graph when I listen to headphones or speakers. Like anyone else, I start playing music and listen first to my few tracks. I build up a picture in my mind and then go back and look at the measurements. I often comment on this as my "first X second impression."

What I find is that once I look at the measurements and develop the EQ, I wind up with an incredibly more reliable assessment of the tonality of the headphone. I can easily determine the impact of any change in the response using EQ. I turn the filter on and off and effect becomes clear. For this reason, I put much more emphasis on this part of the review than "before EQ." What I observe here is defensible. What I observe without measurements is not.

 

[Robbo99999]

I wonder how many people have been adjusting EQ sliders somewhat and thinking it sounds better only to find out that the EQ was not enabled/bypassed. It's so easy to hear changes when one thinks they are doing just that even when nothing changed in reality.

Ha, I did something similar to that once, except that I had two (that's right two!) different EQ's for different headphones activated at the same time in my EqualiserAPO!! It was an HE4XX EQ enabled along with a K702 EQ! I'd just switched to my newer K702 (I have two K702's) and I thought the perception of extra bass was due to the fact that indeed my newer K702 does deliver bass a bit better than my older one, but we were talking a massive EQ bass boost I was accidentally applying - effectively double, however it took listening to a number of different tracks for me to start questioning what was going on and to check my EqualiserAPO settings, I was convinced for quite a long time that it was my assumption that it was my newer K702 exhibiting more bass.....it was super obvious when switched off the HE4XX EQ and was left with the correct K702 EQ only, obvious throughout the frequency range in terms of enjoyment/clarity/etc, but it took quite a while for me to realise what I'd done!

 

[EJH]

I would recommend you watch Amir's video he posted last page, it goes into detail regarding measurements' importance.

I do not think subjective assessments such as sounding kind of dark or having a layer of ice between you and the music are meaningful. It is okay to say these things, this review for example describes the hearing the stealth for the first time like seeing an OLED screen for the first time. These subjective analyses however tend to be nonsense. I don't mean this an assessment of your or Amir's particular subjective claims, but instead a general statement.

When I said subjective assessment in my previous post, I am strictly referring to characterizing flaws of and verifying analysis of measurements. This is a subjective activity and it unfortunately has a chance of being nonsense. I think Amir could do this subjective activity more reliably if he listened to the headphones both before and after analyzing measurements. In particular I think using the stealth as a reference to AB the headphones when listening prior to analyzing measurements would be good practice.

Another term to refer to characterizing flaws of and verifying analysis of measurements besides 'subjective assessment' would be useful, as it is very different than describing a headphone as having a layer of ice or comparing a headphone to an OLED tv.

I've already seen the video, and I support the work Amir is doing here. My characterization of the 650 describes my experience with it and is not meant to hold any validity for others. The point of my comment is that the measurements don't change what I think of the 650 and shows the limits of objectivity when it comes to the analysis of headphones. Subjectivity has to enter into the assessment at some point. That's because headphones are meant to be listened to and experienced, and experience is subjective by nature. Trying to completely purge subjectivity from the analysis of headphones is sheer folly. You have the subject (the listener) and the object (the recorded music or playback device), and the whole point, as I see it, is to take both into account. Otherwise, you're just giving half the story.

 

[Zim]

I've already seen the video, and I support the work Amir is doing here. My characterization of the 650 describes my experience with it and is not meant to hold any validity for others. The point of my comment is that the measurements don't change what I think of the 650 and shows the limits of objectivity when it comes to the analysis of headphones. Subjectivity has to enter into the assessment at some point. That's because headphones are meant to be listened to and experienced, and experience is subjective by nature. Trying to completely purge subjectivity from the analysis of headphones is sheer folly. You have the subject (the listener) and the object (the recorded music or playback device), and the whole point, as I see it, is to take both into account. Otherwise, you're just giving half the story.

TBH your reasoning is all the more reason subjectivity doesn’t matter in analysing headphones as part of a review; headphones are to be listened and experienced.
But of course, the listening experience varies from person to person, reviewer, reader, etc. I wouldn’t want to “purge” subjectivity, but would take it with a massive grain of salt compared to objective measurements.

The “half” of the story you speak of is ultimately between the headphones and the user, not between a reviewer’s subjective listening experience and the reader. An experience that the reader won’t have or share with the reviewer unless for some insane coincidence that the reader shares the exact same head and ear structure as the reviewer.

Anyway this is off-topic from this thread so I’m done chiming in my 2 cents. Perhaps a topic for General Audio.

 

[EJH]

I don’t believe subjective experience varies so much that impressions are completely irrelevant. Why doesn’t Amir just skip the subjective part altogether and just let the measurements speak for themselves? IMO it’s because people would feel that something was missing from the review. At the end of the day, people want to know what the headphone sounds like, even if it’s only what it sounds like to him.

 

[Madlop26]

Both are important. For instance, Ananda and Koss 95X measured poorly and got relatively bad reviews from Amir, while he gave the HD650 a thumbs up. Well, I owned the 650 for two years and tried over and over again to like it. Never did. That headphone left me cold. I found it atrocious for orchestral music, which is what I mostly listen to. Even for rock and pop, I always felt like there was a thin layer of ice between me and the music. They also sounded kind of dark. Meanwhile, I currently own the Ananda and 95X and like them both so much better. That they measured worse than the 650 makes no difference to me. I’m not suddenly going to like the 650 and dislike the other two because of measurements. While I find measurements interesting, when it comes to headphones, I take measurements with a grain of salt. Objectivity is not enough.

Even subjectivity can be scientifically measure and studied; you think you like the Ananda and Koss 95X better than your HD650, one can still wonder, is that and absolute fact? well nope...not until you do a proper blind test, you may think that is unnecessary, but results of blind tests, frequently blows our minds out, that I can tell you..

 

[ifloatoveryou]

Let me make sure I point this out as I have mentioned it a number of times: I do NOT memorize the frequency response graph when I listen to headphones or speakers. Like anyone else, I start playing music and listen first to my few tracks. I build up a picture in my mind and then go back and look at the measurements. I often comment on this as my "first X second impression."

What I find is that once I look at the measurements and develop the EQ, I wind up with an incredibly more reliable assessment of the tonality of the headphone. I can easily determine the impact of any change in the response using EQ. I turn the filter on and off and effect becomes clear. For this reason, I put much more emphasis on this part of the review than "before EQ." What I observe here is defensible. What I observe without measurements is not.

I recall you mentioning that listening to the stealth before measurements was an exception to your usual approach, but this time was not an issue as the stealth measures well. The general impression I have after reading many of your headphone reviews is that you look at the measurements before assessing headphones. I may just be misunderstanding your approach - if you are listening before looking at measurements then my criticism is invalid.

I think your approach to developing eq is good. My criticism is in relation to the indefensible aspects of the review, such as observing a lack of spatial qualities or hearing a wonky sound due to a rough frequency response. If you look at the measurements and expect these things will appear, they most likely will be heard by your ears. Listening and assessing headphones before looking at measurements, perhaps using AB testing, would not make these observations defensible or reliable, but would make them less likely to be imagined.

Again, I want to emphasize that this is not a major criticism. Since this aspect of the review will never be reliable, removing potential bias would not be some drastic improvement.

 

[ifloatoveryou]

I've already seen the video, and I support the work Amir is doing here. My characterization of the 650 describes my experience with it and is not meant to hold any validity for others. The point of my comment is that the measurements don't change what I think of the 650 and shows the limits of objectivity when it comes to the analysis of headphones.

The idea of the harman target is to have a headphone influence the sound minimally. Think of it like looking at an image through glass. Objectivism tries to find transparent glass, but some people prefer tinted glass and that's fine. Objectively looking at headphones will not be able to explain everyone's preferences. Unfortunately people's preferences towards more expensive tinted glass often seems to be a result of clever marketing.

 

[EJH]

Even subjectivity can be scientifically measure and studied; you think you like the Ananda and Koss 95X better than your HD650, one can still wonder, is that and absolute fact? well nope...not until you do a proper blind test, you may think that is unnecessary, but results of blind tests, frequently blows our minds out, that I can tell you..

Subjective experience can be scientifically studied, but it can’t always be measured. I can measure how long it takes me to get from home to work, but I can’t measure how long I experience the trip as being. This holds for both time and distance. And of course objectivity is a modification of subjectivity since the object is always given through the subject. I totally agree with you about the prevalence of subjective bias though, and you’re right: I can’t say for sure that I wouldn’t prefer the sound of the 650 over the others in a blind test since I’ve never been tested.

 

[tusing]

Fantastic interview with Sean Olive, posted by Audioholics today, describing the methodologies and justifications behind the design of the Harman target. Sean Olive mentions the DCA Stealth and @amirm 's review at 51:20, but it's really just in passing. I'd recommend that people watch the whole video, it's very educational!

One interesting aspect I found is that the Harman target was preferred regardless of cultural background or musical/listening experience - even very experienced listeners almost universally preferred the Harman target.

Another interesting aspect was that experienced listeners were almost completely unable to differentiate between Headphone A equalized to sound like Headphone B, versus just Headphone B (with the rare exception of when either headphone might exhibit a significant amount of distortion.) This implies that cup reflections and design really might not play as big of a role as we like to think, and audiophiles might not be as good at distinguishing non-FR aspects as they like to think.

Sean Olive makes it very clear that you don't need to spend $4K to get a headphone that performs extremely well. A lot of the headphones in the $50-$200 range match the Harman target closely. I'd love to see Amir review some of the headphones in blue:

It's funny to imagine this graph extending all the way to $4000, running well off of my screen, and a single dot slightly higher than the JBL Tune 710 representing the DCA Stealth. (Didn't stop me from purchasing the Stealth, though!)

The future of headphones will probably be cheap drivers DSP'd to the Harman target, with some degree of head tracking with binaural reproduction, and audiophiles will be at a loss as to what to spend their money on next.

Like a mechanical watch versus a quartz watch, headphones like the Stealth are very much a novelty for the rich, in that what makes them unique is that they don't need DSP to achieve a high preference rating, but that is immaterial to the sound quality in the end. If Olive is right, you should be able to get Stealth levels of performance for a fourtieth of the price.

 

[MayaTlab]

Another interesting aspect was that experienced listeners were almost completely unable to differentiate between Headphone A equalized to sound like Headphone B, versus just Headphone B (with the rare exception of when either headphone might exhibit a significant amount of distortion.) This implies that cup reflections and design really might not play as big of a role as we like to think, and audiophiles might not be as good at distinguishing non-FR aspects as they like to think.

I think that this might not be a 100% accurate representation of the related papers, which I'm assume are :
https://www.aes.org/e-lib/browse.cfm?elib=16874
and :
https://www.aes.org/e-lib/browse.cfm?elib=18462
and possibly :
https://www.aes.org/e-lib/browse.cfm?elib=17441

From what I understand so far, in the first article (over-ears), the virtual headphones were tested against the real headphones directly on the subjects' heads.
But in the second paper (in ears), the virtual headphones were tested against recordings of the real headphones, made on the GRAS fixture. So in the second case the question of HPTF variability or measurement inaccuracies is lost and the two headphones (real vs. virtualised) were guaranteed to have nearly the same FR (which is definitely what you want to do in the third paper where you need to make sure that FR is a controlled variable). Which is possibly why a better correlation was found for the in ear virtualisation vs. the over ears.

In the over-ears virtualisation article the preference order was actually different between the real vs virtualised HPs. For one HP (HP1) the article attributes the difference to sensory biases, for another one to leakage effects (which is an important part of HPTF variability that Harman evaluated in another article - in which case it's already well established that design matters in a big f*cking way). No explanation was given for HP5's significantly different score I believe. But I'm not certain that all nuisance variables were explored (HP1's perceived spectral balance was a lot better in the real test than in the virtualised one for example).

In all cases the question of HPTF variability or measurement inaccuracies is not enough to invalidate the idea that Harman's targets tend to be generally preferred over other targets, far from it, as in the 2013 article (https://www.aes.org/tmpFiles/elib/20210917/16768.pdf) the "RR_G" target was tested against the "DF_M", DF_MH" (two different diffuse field targets), and "FF" (free field) on both the LCD-2 and HD518 (on the GRAS rig these target should measure identically on both headphones) and the order of preference remained similar. But interestingly the delta between the targets' score was quite different : in the LCD-2 test the RR_G target was only slightly preferred over the DF_M target, the latter being strongly preferred over the DF_MH target, while in the HD518 test the RR_G target was strongly preferred over the DF_M target, and the latter only lightly preferred over the DF_MH target - even though on a GRAS rig they all measured the same and therefore should have logically scored consistently. I'm not certain that this discrepancy can solely be attributed to HPTF variations / measurement inaccuracies pushing the targets above / below the GRAS response if they were measured at the listeners' DRP, as the two tests included additional, different targets that may have biased the way the subjects comparatively rated the constant targets (addition of "RR1_G" in the LCD-2 test, "DF_L" in the HD518 test, and the "no EQ" target - obviously different for each HP - in both cases). But it could be.

My understanding so far is that I think that the question of HPTF variability / measurement inaccuracies may introduce a grey area where the predictive value of Harman's research is less valid. It's not a big deal when even as of 2021 HP manufacturers still sell crap like this :
https://headphonetestlab.co.uk/test-results-manufacturers-a-d-bw-px7
But it might make it difficult to make preference predictions for two HPs that measure similarly or score decently well (example : HD560S vs HD650).

The extent of that grey area may not be that easy to determine. I don't know of that many articles that explored the question of HPTF variability / measurement inaccuracies. It's not easy to measure the actual on-head response of a pair of HPs past 1kHz or so. I believe that these explore these issues :
https://www.aes.org/e-lib/browse.cfm?elib=17699
https://www.aes.org/e-lib/browse.cfm?elib=17242
https://www.aes.org/e-lib/browse.cfm?elib=16877
At lower frequencies for some HPs types it can be very significant. That's been extensively studied and is one of Rtings' most interesting set of measurements IMO : https://www.rtings.com/headphones/tests/sound-quality/frequency-response-consistency
Between let's say 400-1kHz it's probably quite minimal.
Above 5kHz... difficult to know for sure but probably quite important.
And I'm starting to think that in the ear canal gain region we don't have the last word for it yet (particularly I'm starting to feel for ANC over-ears with a robust ANC / feedback mechanism such as the Bose 700 or Airpods Max, which are already quite difficult to accurately measure for various reasons).

My understanding is that some of these variations may be desirable if they correspond to what your individual HRTFs would result in if you were to take the place of the GRAS' mannequin in Harman's "decent room with decent speakers", but some aren't. Again difficult to know the extent of that.

So while Harman's research tends to give credence that once FR is a controlled variable, provided distortion is low enough, HPs are similarly rated, I'm not certain that FR remains a sufficiently well controlled variable in terms of actual on-head response that it makes questions of "cup reflections and design" not that important.

My understanding of these papers may be wrong so feel free to correct me .

 

[Jave]

Fantastic interview with Sean Olive, posted by Audioholics today, describing the methodologies and justifications behind the design of the Harman target. Sean Olive mentions the DCA Stealth and @amirm 's review at 51:20, but it's really just in passing. I'd recommend that people watch the whole video, it's very educational!

One interesting aspect I found is that the Harman target was preferred regardless of cultural background or musical/listening experience - even very experienced listeners almost universally preferred the Harman target.

Another interesting aspect was that experienced listeners were almost completely unable to differentiate between Headphone A equalized to sound like Headphone B, versus just Headphone B (with the rare exception of when either headphone might exhibit a significant amount of distortion.) This implies that cup reflections and design really might not play as big of a role as we like to think, and audiophiles might not be as good at distinguishing non-FR aspects as they like to think.

Sean Olive makes it very clear that you don't need to spend $4K to get a headphone that performs extremely well. A lot of the headphones in the $50-$200 range match the Harman target closely. I'd love to see Amir review some of the headphones in blue:

View attachment 153837

It's funny to imagine this graph extending all the way to $4000, running well off of my screen, and a single dot slightly higher than the JBL Tune 710 representing the DCA Stealth. (Didn't stop me from purchasing the Stealth, though!)

The future of headphones will probably be cheap drivers DSP'd to the Harman target, with some degree of head tracking with binaural reproduction, and audiophiles will be at a loss as to what to spend their money on next.

Like a mechanical watch versus a quartz watch, headphones like the Stealth are very much a novelty for the rich, in that what makes them unique is that they don't need DSP to achieve a high preference rating, but that is immaterial to the sound quality in the end. If Olive is right, you should be able to get Stealth levels of performance for a fourtieth of the price.

I own the Buds Pro and these earphones are pretty awful compared to Samsung's previous Buds+. Too much around 200Hz and 8kHz

 

[Zensō]

It's funny to imagine this graph extending all the way to $4000, running well off of my screen, and a single dot slightly higher than the JBL Tune 710 representing the DCA Stealth. (Didn't stop me from purchasing the Stealth, though!)

While I agree that there is little correlation between price and sound quality in headphones, there is certainly more to it than adhering to the Harman target. Other factors such as comfort, build, and difficult to measure aspects of sound other than frequency response and distortion are at least as important.

At least for Harman, the above graphic tells the story: for them the target is primarily about marketing and sales.