Testing audiophile claims and myths

[bfreedma]

Nope.

I've seen plenty of measurements showing how larger drivers change their parameters over the first few hours... sometimes significantly.
And no speaker designer I know would take measurements without letting the driver run overnight first.
(Obviously whether a given measured change will be audible depends on many factors.)
Since the drivers in headphones operate according to the same mechanical principles, it seems reasonable to assume that they would be subject to similar effects.

However, very few folks have bothered to attempt to perform any proper tests, and there seems to be little interest in doing so.
(Even headphone manufacturers seem to disagree about whether the effect is sigificant or not.)

Of the few tests run - there seem to have been a few that concluded that there are measurable differences - at least with some headphones.
However, none were done with any significant number of different models, or with more than one or two test subjects.
And, even then, the results of listening tests seem to have been inconclusive.
Headphone sound is also affected by their fit, which changes slightly every time you put them on, and makes comparisons even more difficult.
(It's also possible that, as with full size speaker drivers, different models may be affected quite differently.)

Therefore, with a specific model of headphone, I wouldn't presume to know if there will be any sort of burn-in effects or not.
If I were trying to take measurements, I would probably allow a headphone to burn in overnight, simply to eliminate the possibility that they might change.
(If a change occurs after you take measurements, then your measurements will be wrong; but, if no change occurs, then no harm done.)

https://www.jabra.com/blog/headphone-burn-in-fact-or-fiction/

https://www.tested.com/tech/accessories/459117-science-and-myth-burning-headphones/

Since the construction of headphones varies considerably...
I suggest that anyone requiring a specific answer test the particular model they are interested in...
(Personally I don't care enough to bother.)

Here we go again - you make a claim then refuse to support it beyond posting that "you've seen plenty of measurements", none of which you can produce. And that you "don't care enough to bother". So essentially, your original post seems to be forum trolling (since you don't have supporting evidence and don't care enough to bother).

What makes this a bit more interesting is that your organization builds and sells speakers. Does Emotiva "burn in" their speakers or not? If so, then there must be a reason and you would presumably have the data to support it - both for initial burn in and long term use. A simple set of pre and post burn in FR graphs would be a great start. Adding a CSD waterfall would be even better.

Since you claim this phenomenon is "especially noticeable with ported speakers" and your company produces ported speakers, you surely must have supporting data...

 

[Killcomic]

I burnt my old near fields in for about 23,000 hours and they sounded rubbish when I was done.

To be honest, mine sounded really bad too when I burnt them in the oven for 8 hours.

 

[KeithEmo]

Yes.... here we go again.
My original post was a simple answer to a simple question.

Someone asked whether headphones burn-in.

I pointed out that speakers do indeed show changes in their measured performance over time...
Since headphone drivers are built exactly like little speaker drivers, it would only be reasonable to expect similar changes to occur in their performance over time.
And, since headphone drivers vary widely in terms of construction and the materials used, I would expect this to also vary widely.

It is close to a first principle of mechanical engineering that all flexible springy materials - like rubber and plastic - change their springiness after repeated flexing...
(And, since the suspensions of speakers are made from this type of material, this applies to them.)
I'm sure you can find the mechanical properties of the plastics used to make headphone diaphragms documented somewhere.

To answer your actual questions (about speakers made by Emotiva):

-
During the development process we DO burn in both individual drivers and complete speakers before measuring or testing them.
It is most common in the industry to leave low frequency filtered pink noise running overnight for this purpose - which is what we usually do.
(Sometimes we simply ensure that someone has been listening to them for a few days before taking measurements.)
Our speaker designers have found, from long experience, that the measured parameters on most speaker drivers do in fact change over the first few hours of use.
(As far as I know, that change is always in the same direction; the suspension gets slightly softer and the free air resonance gets slightly lower; although some change a lot while other change very little.)
We don't bother to take or keep measurements before the drivers are burned in - simply because we don't consider them to be representative of the speaker's typical performance.
(We have no interest in plotting how rapidly the parameters change... all we're interested in is ensuring that the measurements we take will represent their performance through most of their usable life.)

-
We DO NOT burn in our production speakers before shipping them; and we DO NOT burn in the individual drivers before assembling them into speakers.
We DO NOT recommend that anyone burn-in our speakers before listening to them, nor do we specify that they will change after burn in.
However, when people specifically ask, we tell them that "they may notice a slight change in sound over the first few days of use".

-
All of the specifications and performance claims me make for our speakers should be considered to be "after a reasonable amount of burn-in".
("After a week or so of use at typical listening levels".)

I have heard that, in the past, some manufacturers burned in individual drivers before initially testing them.
The reason was claimed to be that, because of inconsistencies in manufacturing, different units or batches might change to different degrees.
Therefore, individual units were first burned in, until they reached a stable operating characteristic, before being sorted, graded, and matched.
I suspect that modern construction materials are consistent enough that there is no longer any justification for doing this.

With a ported speaker, the cabinet is tuned to the free air resonance of the driver, among other things.
When the spring constant changes, the tuning match between the driver and cabinet will also change, which can have a significant effect on both frequency response and damping.
The degree to which this affects performance will depend on several different design parameters - which will be different for each speaker model.
As a broad generalization, in a sealed enclosure, the driver will generally experience a single-order roll off, which will shift slightly as the resonance changes.
This will generally result in a smaller and more benign difference if there is a slight mismatch.
(And, as I mentioned above, we have never bothered to measure or record this, since we are really only interested in how the speaker performs once it is "operating normally".)

As as aside, although we haven't tested it, I will state that I personally have never NOTICED an audible change during the burn in period with any of our speakers.

Here we go again - you make a claim then refuse to support it beyond posting that "you've seen plenty of measurements", none of which you can produce. And that you "don't care enough to bother". So essentially, your original post seems to be forum trolling (since you don't have supporting evidence and don't care enough to bother).

What makes this a bit more interesting is that your organization builds and sells speakers. Does Emotiva "burn in" their speakers or not? If so, then there must be a reason and you would presumably have the data to support it - both for initial burn in and long term use. A simple set of pre and post burn in FR graphs would be a great start. Adding a CSD waterfall would be even better.

Since you claim this phenomenon is "especially noticeable with ported speakers" and your company produces ported speakers, you surely must have supporting data...

^ Seems reasonable to give headphones burn-in time just in case the sound changes, but doesn't seem reasonable to conclude that the sound changed due to burn-in unless there's evidence which supports that conclusion and rules out other factors. Audiophiles typically never have such evidence, yet the belief in burn-in is rampant. Most people trust their ears way too much.

 

[KeithEmo]

Agreed.

One article I read reasonably suggested an interesting alternative to the idea of significant driver burn-in.
They noted that even slight differences in the fit of headphones can have a major effect on bass response.
They suggested that the biggest change over time might be due to the ear pads settling into the shape of the listener's head and so providing a better seal.

They noted one test showing a 10+ dB difference in bass response due to adding eyeglasses to their dummy head plus headphone setup.
(The eyeglass frames compromise the quality of the seal between the listener's head and the headphones.)

The fact is that the majority of mechanical systems with moving parts do experience some degree of burn in....
And that is especially true for anything that includes flexible or springy plastic or rubber parts....
Therefore, it seems logical to assume that the same would be true for headphones....

I cannot imagine why this subject is even somewhat interesting.
Once you've listened to your speakers or headphones for a few days they'll be "burned in"... if it matters.
Or, if you're really concerned about it, then simply leave the music playing on your headphones or speakers overnight for a day or two.
If they really change or benefit due to burn in then you will have achieved that change.
And, if not, then no harm done, and no money spent.
It hardly seems worth worrying about either way.

The fact is that the majority of mechanical systems with moving parts do experience some degree of burn in....
And that is especially true for anything that includes flexible or springy plastic or rubber parts....
Therefore, it seems logical to assume that the same would be true for headphones and speakers....
However, testing it for different models and types of headphones would be a lot of work, and it hardly seems worth the bother.
(It's something that may or may not serve a purpose, only happens once for a given pair of headphones, and doesn't cost anything to do.)

^ Seems reasonable to give headphones burn-in time just in case the sound changes, but doesn't seem reasonable to conclude that the sound changed due to burn-in unless there's evidence which supports that conclusion and rules out other factors. Audiophiles typically never have such evidence, yet the belief in burn-in is rampant. Most people trust their ears way too much.

 

[bfreedma]

Yes.... here we go again.
My original post was a simple answer to a simple question.

Someone asked whether headphones burn-in.

I pointed out that speakers do indeed show changes in their measured performance over time...
Since headphone drivers are built exactly like little speaker drivers, it would only be reasonable to expect similar changes to occur in their performance over time.
And, since headphone drivers vary widely in terms of construction and the materials used, I would expect this to also vary widely.

It is close to a first principle of mechanical engineering that all flexible springy materials - like rubber and plastic - change their springiness after repeated flexing...
(And, since the suspensions of speakers are made from this type of material, this applies to them.)
I'm sure you can find the mechanical properties of the plastics used to make headphone diaphragms documented somewhere.

To answer your actual questions (about speakers made by Emotiva):

-
During the development process we DO burn in both individual drivers and complete speakers before measuring or testing them.
It is most common in the industry to leave low frequency filtered pink noise running overnight for this purpose - which is what we usually do.
(Sometimes we simply ensure that someone has been listening to them for a few days before taking measurements.)
Our speaker designers have found, from long experience, that the measured parameters on most speaker drivers do in fact change over the first few hours of use.
(As far as I know, that change is always in the same direction; the suspension gets slightly softer and the free air resonance gets slightly lower; although some change a lot while other change very little.)
We don't bother to take or keep measurements before the drivers are burned in - simply because we don't consider them to be representative of the speaker's typical performance.
(We have no interest in plotting how rapidly the parameters change... all we're interested in is ensuring that the measurements we take will represent their performance through most of their usable life.)

-
We DO NOT burn in our production speakers before shipping them; and we DO NOT burn in the individual drivers before assembling them into speakers.
We DO NOT recommend that anyone burn-in our speakers before listening to them, nor do we specify that they will change after burn in.
However, when people specifically ask, we tell them that "they may notice a slight change in sound over the first few days of use".

-
All of the specifications and performance claims me make for our speakers should be considered to be "after a reasonable amount of burn-in".
("After a week or so of use at typical listening levels".)

I have heard that, in the past, some manufacturers burned in individual drivers before initially testing them.
The reason was claimed to be that, because of inconsistencies in manufacturing, different units or batches might change to different degrees.
Therefore, individual units were first burned in, until they reached a stable operating characteristic, before being sorted, graded, and matched.
I suspect that modern construction materials are consistent enough that there is no longer any justification for doing this.

With a ported speaker, the cabinet is tuned to the free air resonance of the driver, among other things.
When the spring constant changes, the tuning match between the driver and cabinet will also change, which can have a significant effect on both frequency response and damping.
The degree to which this affects performance will depend on several different design parameters - which will be different for each speaker model.
As a broad generalization, in a sealed enclosure, the driver will generally experience a single-order roll off, which will shift slightly as the resonance changes.
This will generally result in a smaller and more benign difference if there is a slight mismatch.
(And, as I mentioned above, we have never bothered to measure or record this, since we are really only interested in how the speaker performs once it is "operating normally".)

As as aside, although we haven't tested it, I will state that I personally have never NOTICED an audible change during the burn in period with any of our speakers.

So many words. All utterly absent of evidence of claimed AUDIBLE burn in/break in.

I’ll try just one more time Keith- can you produce hard evidence of audible changes due to headphone break in. Or speakers. A link to an appropriate article(s) or measurements would be sufficient - no novella necessary.

 

[castleofargh]

I did a response test with tones side by side on a burned in and brand new set of Oppo PM-1s. I couldn't detect any difference. But I imagine high end cans with tighter tolerances are less likely to change.

that IMO is a defective test method. if even that doesn't make you feel a difference, you've at least got your own answer to the question "should I bother with burn in?". but measured variations from pair to pair are often too big to assume that they're accurate copies of each others. also how do we switch from headphone to headphone in the delays suggested for noticing small differences in listening tests? IDK.

I'm tempted to assume that the one and only legit purpose of burn-in is to get beyond the time period where mechanical failures have the highest statistical chances of occurring. but I'm guessing that many manufacturers already do that themselves if only to minimize RMA and similar fun like having many people crying online that the product is crap and broke after a day.

If I were trying to take measurements, I would probably allow a headphone to burn in overnight, simply to eliminate the possibility that they might change.
(If a change occurs after you take measurements, then your measurements will be wrong; but, if no change occurs, then no harm done.)

the other name for this is superstition.

evidence of a given effect is what should always matter, when getting that effect was the reason why we did something in the first place. if you do something to reassure yourself and you do get reassured, then I guess you're right to keep doing it as you've achieved the desired effect. but if you honestly burn in gears so that they sound their best when you first use them, then I do not understand how you can be satisfied with "no harm done" as a reason to keep doing it.




my views on the all burn-in concept are that it's yet another trick that audiophiles came up with to avoid having to look in a mirror.
it goes along with banning blind test from most forums and pushing an aggressive anti measurement movement for decades.
all those things keep proving how imperfect and full of crap we humans are. so let's get rid of them and enjoy dreaming that we're perfect and consistent spectrum analyzers. and dreaming that our feelings were indeed plain objective reality about the gear all along.
I do not know how much change can occur to some specific headphone driver, but I do know that if we go take the last 20 people who claimed that their headphone "burned-in" significantly, none of them will have any evidence for their claim. and most, if not all of those who didn't make it all up in their mind thanks to flawed memory, will in fact have noticed a change due to placement, pad wear, or simply a change in listening level as they most likely were listening louder than usual when they did their first "critical listening". even if something is going on with the driver, I believe we have enough data to say that those other causes of change will almost always be of higher magnitude and more noticeable as they impact our impressions of the frequency response.
so let's drop the act and simply admit that the all burn in thing is a façade for people who can't let go of the illusion of their own consistency over time. it's a lie to make people feel better about themselves by blaming everything on the gears.

 

[Phronesis]

Agreed.

One article I read reasonably suggested an interesting alternative to the idea of significant driver burn-in.
They noted that even slight differences in the fit of headphones can have a major effect on bass response.
They suggested that the biggest change over time might be due to the ear pads settling into the shape of the listener's head and so providing a better seal.

They noted one test showing a 10+ dB difference in bass response due to adding eyeglasses to their dummy head plus headphone setup.
(The eyeglass frames compromise the quality of the seal between the listener's head and the headphones.)

The fact is that the majority of mechanical systems with moving parts do experience some degree of burn in....
And that is especially true for anything that includes flexible or springy plastic or rubber parts....
Therefore, it seems logical to assume that the same would be true for headphones....

I cannot imagine why this subject is even somewhat interesting.
Once you've listened to your speakers or headphones for a few days they'll be "burned in"... if it matters.
Or, if you're really concerned about it, then simply leave the music playing on your headphones or speakers overnight for a day or two.
If they really change or benefit due to burn in then you will have achieved that change.
And, if not, then no harm done, and no money spent.
It hardly seems worth worrying about either way.

The fact is that the majority of mechanical systems with moving parts do experience some degree of burn in....
And that is especially true for anything that includes flexible or springy plastic or rubber parts....
Therefore, it seems logical to assume that the same would be true for headphones and speakers....
However, testing it for different models and types of headphones would be a lot of work, and it hardly seems worth the bother.
(It's something that may or may not serve a purpose, only happens once for a given pair of headphones, and doesn't cost anything to do.)

Physically, it's plausible that some properties of drivers would change with use, and that could generate a measurable difference in sound. And I've seen some measurement data to that effect. So there shouldn't be any controversy there.

Where it gets silly is when audiophiles talk about 50 or 100 or 300+ hours of burn-in, with that burn-in changing the sound from having some noticeable problems to being sublimely good, with all the problems fixed. If the drivers were really changing that much, I'd say they were poorly designed and/or poorly built, and I'd worry about the sound eventually degrading due to things getting too 'loose'. A much more plausible explanation IMO is that the perception of listeners changes over time such that their ears/brains adjust what's perceived so that it sounds more 'correct', based on a model of correct sound built over time from prior listening experiences. Changes in pads, etc. could also be a factor, but I wouldn't expect that to consistently change the sound in the direction of improving it.

BTW, as evidence of my being a double agent, I got locked out of the Z1R thread for a week due to my comments about burn-in, cables, perception, etc. I don't blame the mods for that, it's what they had to do in response to outcry from people in the thread with an aversion to 'science' and Z1R owners who couldn't bear to have the image of the Z1R maligned. This stuff can really be worse than politics and religion. I'm not a proper Sound Science card holder, but I feel a lot more comfortable talking with you guys than people in the rest of head-fi. Regardless of what we agree on or don't, at least we can have real discussions and debates here.

 

[Phronesis]

I'm tempted to assume that the one and only legit purpose of burn-in is to get beyond the time period where mechanical failures have the highest statistical chances of occurring. but I'm guessing that many manufacturers already do that themselves if only to minimize RMA and similar fun like having many people crying online that the product is **** and broke after a day.

The burn-in period is also a good way to have people keep the product past the return period: "I'm not quite happy with the sound, but they say it needs 50-100 hours of burn-in, the return period is about to end, and I've only done 25 hours. I'll guess I'll keep it and wait for it to sound as good as everyone says it will." (Keep hope alive!)

 

[CactusPete23]

Changing Directions here a bit with a question.

Are there any Good Mid-Fi Single Ended Portable DAP's out there? Or Do they need to be balanced to sound better? i.e. Is this myth or reality?

When I look at getting a better sounding Portable DAP, It looks like most manufacturers today quickly jump to Separate DAC's and Amps to get balanced output. It is like there is an expectation that "balanced" makes a player better automatically. And when I look for a mid-fi or better DAP, I can't seem to find a many good ones that are just single ended. Somehow, I think that a single ended DAP with just one DAC and Amp, but using good components and design, could sound better (And be lower cost, lower power usage, ligher weight) than lots of the Balanced DAP's out there? (Looking for something to drive Efficient Headphones and IEMs for portable use. )

So, is it a reality that a mid to high fi Portable DAP must be balanced? Or can a good single ended DAP provide better sound quality that many Balanced DAP's ?

And then IF a really good single ended DAP is being made. who makes them? (Or is this a design/marketing opportunity !)


Thanks!

PS: I am not sure if this question fits this thread. So please point me in the right direction if the experts in the thread think I'm in the wrong place. Thanks ! Tried searching the forums, but could not find this specific topic being discussed...

 

[KeithEmo]

Let's make this simple...

No, I have no intent of producing evidence that burn-in produces audible effects in any particular product.
Do you plan to introduce any evidence that, in a specific headphone or speaker, burn in does NOT produce an audible change?
Or are we both just stating our opinions on the subject?

I'm not personally interested in having a debate on the subject.
And neither am I especially interested in convincing anyone either way.

So many words. All utterly absent of evidence of claimed AUDIBLE burn in/break in.

I’ll try just one more time Keith- can you produce hard evidence of audible changes due to headphone break in. Or speakers. A link to an appropriate article(s) or measurements would be sufficient - no novella necessary.

 

[KeithEmo]

That is an excellent point - and one to keep in mind...
(And perhaps a good reason to make sure that you apply the recommended burn-in before the return period expires.)

And there is also another slightly less sinister possibility...
We humans tend to grow to prefer things we are familiar with...
Perhaps they're just making an excuse for you to keep it long enough to become familiar with it and decide you like it...
(And, by suggesting that you listen for differences, they are providing even more incentive for you to focus on how it sounds.)

In all fairness, if you've been listening to something for weeks, and still haven't decided that you like it...
Then you probably don't like it enough to buy it.

The burn-in period is also a good way to have people keep the product past the return period: "I'm not quite happy with the sound, but they say it needs 50-100 hours of burn-in, the return period is about to end, and I've only done 25 hours. I'll guess I'll keep it and wait for it to sound as good as everyone says it will." (Keep hope alive!)

 

[KeithEmo]

I absolutely agree.

If there are going to be audible changes due to mechanical "break in"......
I would expect them to be most significant after the first few hours ......
If you haven't noticed a significant change, in the right direction, by then... then I wouldn't be hoping for it to come along later.

What we're talking about here is mostly an initial stiffness in flexible or elastic products....
Like leather or plastic shoes or leather gloves that get softer after being worn for a few days....
And the time scale should be something similar....

Likewise, as you suggest, it also provides time for our brains to normalize and start considering the sound of that particular product as "normal and right".
However, if they're going to occur, both of these effects typically occur over the first few days or hours...

Physically, it's plausible that some properties of drivers would change with use, and that could generate a measurable difference in sound. And I've seen some measurement data to that effect. So there shouldn't be any controversy there.

Where it gets silly is when audiophiles talk about 50 or 100 or 300+ hours of burn-in, with that burn-in changing the sound from having some noticeable problems to being sublimely good, with all the problems fixed. If the drivers were really changing that much, I'd say they were poorly designed and/or poorly built, and I'd worry about the sound eventually degrading due to things getting too 'loose'. A much more plausible explanation IMO is that the perception of listeners changes over time such that their ears/brains adjust what's perceived so that it sounds more 'correct', based on a model of correct sound built over time from prior listening experiences. Changes in pads, etc. could also be a factor, but I wouldn't expect that to consistently change the sound in the direction of improving it.

BTW, as evidence of my being a double agent, I got locked out of the Z1R thread for a week due to my comments about burn-in, cables, perception, etc. I don't blame the mods for that, it's what they had to do in response to outcry from people in the thread with an aversion to 'science' and Z1R owners who couldn't bear to have the image of the Z1R maligned. This stuff can really be worse than politics and religion. I'm not a proper Sound Science card holder, but I feel a lot more comfortable talking with you guys than people in the rest of head-fi. Regardless of what we agree on or don't, at least we can have real discussions and debates here.

 

[bfreedma]

Let's make this simple...

No, I have no intent of producing evidence that burn-in produces audible effects in any particular product.
Do you plan to introduce any evidence that, in a specific headphone or speaker, burn in does NOT produce an audible change?
Or are we both just stating our opinions on the subject?

I'm not personally interested in having a debate on the subject.
And neither am I especially interested in convincing anyone either way.

Stop playing games.
You made a specific claim - the burden of proof is entirely yours. Asking me to provide anything is simply deflection.
If you had simply stated you had an opinion in your initial post on the topic, I wouldn’t have responded.

 

[Phronesis]

Stop playing games.
You made a specific claim - the burden of proof is entirely yours. Asking me to provide anything is simply deflection.
If you had simply stated you had an opinion in your initial post on the topic, I wouldn’t have responded.

FWIW, I didn't read Keith's comments as intending to support the audiophile belief that extended burn-in can make a substantial difference.

Also, I've seen some measurement data showing some differences in speakers due to burn-in, but the differences were relatively small, and if audible at all, likely to be insignificant. Please don't ask me to track down the links, I'm still feeling lazy after the holidays!

 

[castleofargh]

Changing Directions here a bit with a question.

Are there any Good Mid-Fi Single Ended Portable DAP's out there? Or Do they need to be balanced to sound better? i.e. Is this myth or reality?

When I look at getting a better sounding Portable DAP, It looks like most manufacturers today quickly jump to Separate DAC's and Amps to get balanced output. It is like there is an expectation that "balanced" makes a player better automatically. And when I look for a mid-fi or better DAP, I can't seem to find a many good ones that are just single ended. Somehow, I think that a single ended DAP with just one DAC and Amp, but using good components and design, could sound better (And be lower cost, lower power usage, ligher weight) than lots of the Balanced DAP's out there? (Looking for something to drive Efficient Headphones and IEMs for portable use. )

So, is it a reality that a mid to high fi Portable DAP must be balanced? Or can a good single ended DAP provide better sound quality that many Balanced DAP's ?

And then IF a really good single ended DAP is being made. who makes them? (Or is this a design/marketing opportunity !)


Thanks!

PS: I am not sure if this question fits this thread. So please point me in the right direction if the experts in the thread think I'm in the wrong place. Thanks ! Tried searching the forums, but could not find this specific topic being discussed...

sadly you will probably never find the measurements relevant for that. to start with the elephant in the room, "balanced" for amateur audio gear can mean almost anything so long as you end up with more than 3 pins for both drivers. so from the get go, different "balanced" DAPs may not even be offering the same designs and specs. it's just another one of those oversimplified stuff that we audiophiles love to draw false conclusions upon because it makes things look easy and clear. the trend for expensive balanced DAPs is exactly that IMO. it's yet another occasion to have something special requiring special cables, so of course it has that elite smell we all want.
with that said, I would expect some differences between single ended and balanced on a same device, mostly depending on the headphone/IEM used. probably the balanced output will have higher impedance and that can make a pretty obvious change in signature for some IEMs with chaotic impedance curves reaching super low values. higher impedance output on DAPs is nowadays supposed to be to audiophiles what the sun is to vampires, but now the trend is to go balanced so we all pretend like low impedance output isn't important anymore. I remember seeing the exact same thing with A&K and their crap first DAP at ludicrous price. everything was wrong the impedance output was stupidly high, but magically the impedance output stopped being relevant for a while because the expensive stuff didn't do it right. if it's expensive, someone will say that it sounds amazing. that's ultimately the law around here. actual performances rarely dictate what the FOTM will be.

it's also possible that when using a crazy low impedance IEM with very average amp sections, the crosstalk levels may rise up to the point of being noticeable. in such a case a balanced output might just offer the extra separation that makes a subjective difference? I'm really just guessing here but under the wrong conditions that seems perfectly possible.
in my mind there is no doubt that a proper single ended design can do just as well if not better than balanced. but when forced to design something within a given size, using a given power source(again because of the size and weight restrictions), it's most certainly a bad idea to estimate the expected sound fidelity based on the output plug or some chipset's name. actual measurements into various loads should set the hierarchy for fidelity. but we seldom find such measurements into the loads relevant to modern TOTL IEMs. so beside trying and hoping to get lucky, I really don't know what to do.
the one brand I can think of, where the balance output trend may really be a blessing, is Sony. because they have decided to stick with their own weirdo class D system that has been great for battery life, but not so great for everything else. and for years, SONY has struggled to get a DAP that could get above 0.5Vrms and they still had poor output impedance anyway. most really didn't measure best at full output. so for Sony, an easy trick to double the output voltage may really have been the difference between passable output and pretty good output. personally I loved Sony when the expensive stuff were the tiniest revolutionary ones. not so much now when the expensive stuff has some bulky machine casing to "show" why it's expensive. but that's just me whining about my personal preferences ^_^.

all in all I hate special plugs because of all the extra expenses to ensure cable compatibility. and I don't like how balanced stuff cost more because they're balanced so balanced must be better because it costs more because it's balanced because...
but a good design will be good no matter if it's balanced or SE. if I was on the market for a new DAP now, I wouldn't let something like balanced vs SE decide things for me. there are enough criteria and personal desires to filter out DAPs until only a handful remains to chose from. buttons, functions, size, battery life, etc.