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Review and Measurements of Okto DAC8 8Ch DAC & Amp

amirm

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For example, one significant measurable difference between ESS DAC's and others is their impulse response, but Amirm didn't measure it. Here's what Keith L. of Emotiva had to say about the issue:

"The signal passing through a DAC is often altered in many subtle but significant ways... many of which involve timing. However, most of those alterations are somewhat complex to measure, and VERY complex to interpret. If you look at the analog output of several different DACs with a variety of input test signals, you will see significant differences. Many manufacturers and magazine reviewers publish certain of these characteristics - like 'impulse response' - and those measurements are in fact different for Sabre DACs than for most others. [emphasis added] Unfortunately, even when looking directly at the images of those signal characteristics, it isn't always obvious what a given difference represents in terms of SOUND.

"What is happening is that Sabre DACs have certain differences from most other DACs in terms of how they handle some sorts of impulse signals.
Because we're talking about subtle differences, and because no current DAC is perfect in this context, it may be difficult to suggest which ones are 'more correct.' (Most of us here at Emotiva agree that the DACs we've chosen to use produce an output that we perceive as being more accurate to the original than Sabre DACs.) However, if you compare oscilloscope images of certain test signals, the differences themselves are relatively easy to see. And there are certain commonalities in how they are perceived by the majority of human listeners.

"When comparing a Sabre DAC to 'an average DAC' from any of several other brands (with similar basic specs).....
- Some listeners fail to notice any significant difference
- Most listeners who notice a difference and LIKE Sabre DACs describe them as sounding 'more detailed' or 'more revealing'
- Most listeners who notice a difference and DISLIKE Sabre DACs describe them as sounding 'etched' or 'grainy' or 'bright' or even 'overly detailed'

[emphasis added]
Please don't appeal to authorities that don't have the proper qualifications. Here is Keith's: https://www.linkedin.com/in/keith-levkoff-a451b231/

1565564514143.png


He has no background in the above topics. He is citing no research. No controlled testing. No discussion of proper psychoacoustics.

It is all typical internet chatter and lay intuition devoid of any real science. "Some sort of impulse signals?" There is only one impulse signal, not different sorts.

"Most of them at emotiva have decided what sounds good?" Oh, I better go and re-write decades of research in audio now.

"Some or most listeners" notice a difference? In what way? In a controlled test or the totally unreliable sighted testing audiophiles do?

If you are here, you should listen to proper audio science and engineering. Not marketing statements written by a tech writer who doesn't have deep understanding of these topics.

BTW, I have read Keith's posts elsewhere and he is a nice individual but technical, he is not.
 

josh358

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Who says it is one of the most used audio test signals? A 1 kHz tone fits that definition far, far more than an impulse signal.

An impulse signal is highly useful in characterizing a black box system due to its finite spectrum. That analysis has little to do with what is or is not audible.


What?
Not sure what I can add to that. As I said, they're Fourier transforms of one another, frequency and time domain respectively, so each determines the other uniquely. This is why we convolve the impulse response to apply a digital filter to a signal, and why it can be generated in an audio analysis program from a frequency sweep. And needless to say, frequency response has a *lot* to do with what is audible!
 

amirm

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Not sure what I can add to that. As I said, they're Fourier transforms of one another, frequency and time domain respectively, so each determines the other uniquely. This is why we convolve the impulse response to apply a digital filter to a signal, and why it can be generated in an audio analysis program from a frequency sweep. And needless to say, frequency response has a *lot* to do with what is audible!
Frequency response is measured using well, frequency response! You can't determine the frequency response using an impulse visually anyway. That is a time domain signal, not frequency domain. You would have to convert that response using FFT to see the spectrum.

Impulse responses are used to sell all manner of audio electronics with completely poor basis in audibility or usability. Here is Rob Watts of Chord fame telling you the same thing I say:



Don't let your familiarity with usefulness of impulse response in engineering, with its use in audio. The former is absolutely true and valuable. The latter, mostly not.
 

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Please don't appeal to authorities that don't have the proper qualifications. Here is Keith's: https://www.linkedin.com/in/keith-levkoff-a451b231/

View attachment 31148

He has no background in the above topics. He is citing no research. No controlled testing. No discussion of proper psychoacoustics.

It is all typical internet chatter and lay intuition devoid of any real science. "Some sort of impulse signals?" There is only one impulse signal, not different sorts.

"Most of them at emotiva have decided what sounds good?" Oh, I better go and re-write decades of research in audio now.

"Some or most listeners" notice a difference? In what way? In a controlled test or the totally unreliable sighted testing audiophiles do?

If you are here, you should listen to proper audio science and engineering. Not marketing statements written by a tech writer who doesn't have deep understanding of these topics.

BTW, I have read Keith's posts elsewhere and he is a nice individual but technical, he is not.
No, this is the only thing I think I've read from him. I assume he's passing on what Emotiva's engineers told him. But I'd be the first to say that establishing this relationship is speculative. All I know is that ESS says that the impulse response of their feedback loop affects the sound. But whether it's the source of the "Sabre glare" I don't know. (I've heard that in careful, level-matched A/B comparisons, and wanted to ABX it when I had the DAC8 here but had to send it back before I could solve the problems with JRiver's zones feature.) If someone wants to wait for an ABX test before accepting the presence of Sabre glare, that's perfectly all right, I'm not really interested in convincing anybody. My personal interest here is in correlating and what, independently, many others hear (I learned about it only after I'd first heard it on the Exasound e28 I'd bought and did a search) , and as most of the measurements of Sabre DAC's are well nigh perfect, I wondered (and continue to wonder) whether this has something to do with it.

BTW, I can't even say which of the DAC's was accurate, just that they were different in this regard (and in some others about which I'm personally less certain because they were a lot subtler). A good analog source would I think be the best way to determine that, and I no longer have one.
 

amirm

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All I know is that ESS says that the impulse response of their feedback loop affects the sound. But whether it's the source of the "Sabre glare" I don't know.
I do. :) What ESS says is not relevant. What they can show in controlled listening test is. And they have none.

The Sabre glare is just a fish story created online by lay people who don't have any understanding of the real audio science. Audiophiles cannot tell gross distortions in all manner of audio gear and all of a sudden they can hear some subtlety in a DAC? Not possible. I have tested and listened to 200+ DACs. There is no such thing. Please don't believe in this nonsense and let it bias you in your listening tests.

If someone wants to wait for an ABX test before accepting the presence of Sabre glare, that's perfectly all right, I'm not really interested in convincing anybody.
Your posts, quotes, etc. say otherwise. That is why I am responding so that we don't have myths presented as truth in audio. When you have a controlled listening test, make sure you document it fully and present it here in a separate thread. I will save you the grief and tell you that will fail in this task but it is up to you if you want to proceed anyway. :)
 

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Frequency response is measured using well, frequency response! You can't determine the frequency response using an impulse visually anyway. That is a time domain signal, not frequency domain. You would have to convert that response using FFT to see the spectrum.

Impulse responses are used to sell all manner of audio electronics with completely poor basis in audibility or usability. Here is Rob Watts of Chord fame telling you the same thing I say:



Don't let your familiarity with usefulness of impulse response in engineering in audio. The former is absolutely true and valuable. The latter, mostly not.
Sure, you can't do a Fourier transform visually, but impulse response is nevertheless a useful measurement of audio equipment, since just as the frequency response allows us to quickly evaluate frequency domain issues, the impulse response allows us to quickly evaluate time domain ones. And believe me, it is used, forex I've been working with a designer for a major speaker manufacturer for the last couple of years and he uses impulse response measurements all the time.

Interesting Powerpoint, though, with a good point, though I don't see its applicability here -- we aren't talking about preringing.
 

amirm

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Sure, you can't do a Fourier transform visually, but impulse response is nevertheless a useful measurement of audio equipment, since just as the frequency response allows us to quickly evaluate frequency domain issues, the impulse response allows us to quickly evaluate time domain ones. And believe me, it is used, forex I've been working with a designer for a major speaker manufacturer for the last couple of years and he uses impulse response measurements all the time.
A DAC is not a speaker. A DAC has to have by definition bandwidth limited signal input to it. The ADC assures that. An impulse signal created in a computer completely violates that with its infinite bandwidth. A speaker is a different animal with no requirement for pre-limiting the bandwidth of what goes to it.

Even in sound reproduction (speaker and rooms) impulse graphs are misunderstood and misinterpreted. I won't get into it now but will emphasize again that notions of timing/phase that audiophiles have is almost entirely incorrect. Do not fall for any of it without controlled testing.
 

josh358

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I do. :) What ESS says is not relevant. What they can show in controlled listening test is. And they have none.
The Sabre glare is just a fish story created online by lay people who don't have any understanding of the real audio science. Audiophiles cannot tell gross distortions in all manner of audio gear and all of a sudden they can hear some subtlety in a DAC? Not possible. I have tested and listened to 200+ DACs. There is no such thing. Please don't believe in this nonsense and let it bias you in your listening tests.[/QUOTE]
I've been doing this a long time, Amir, in professional audio. I have a pretty good handle on what we can and can't hear, and how easy it is to be misled, which is why I'm a strong believer in blind testing, as are many of the audio designers I know, and at a minimum do level-matched A/B switching (since in retirement I don't always have access to a helper). But I'd have to disagree with you about the people who evaluate DAC's. No, I wouldn't personally listen to some random audiophile who thinks that cables are directional. There's more BS in consumer audio than there is in a cattle ranch. But as I think you know, there are a few people who have done exhaustive A/B comparisons, and I've been impressed that they independently hear what I do -- to me, always a sign that both of us are probably hearing something real.

I'd have to disagree that what ESS says isn't relevant. But we're coming from different perspectives here. I'm a working engineer, or was. I've done plenty of blind tests over the years, and have a pretty good idea of what one can hear as a result. If designers waited for a blind test of every product, nothing would ever get done, equipment would never improve. I'd note for example that it was many, many years before someone successfully ABX'd high resolution audio -- and that I had long discussions in the 80's with my good friend David Smith about the work he was doing at Sony, and we discussed the very same audible differences that are being discussed and ABX'd today. Quite simply, they were aware of much that the press, the public, and even most audio engineers weren't, because they were doing the most R&D. So personally, I'm not going to write off Sony, because that's been true of just about every designer I've known over the years.

But again, I'm not interested in turning this site into Stereophile, and I'm a bit chagrined at the reaction to what I thought was a good faith report of my experience with the Dac8, one that might in its own way be of interest to those considering buying it, as I did. This is my personal philosophy and experience, after going back and forth on the issue of subjective differences several times over the years and ending up firmly in the moderate camp, and it isn't my intention to force it on anyone else, it's a discussion that's been had to death. I'm more curious in the technical reasons/measurement correlates for what I hear, and why you didn't hear what I did in your own subjective comparisons.
 

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A DAC is not a speaker. A DAC has to have by definition bandwidth limited signal input to it. The ADC assures that. An impulse signal created in a computer completely violates that with its infinite bandwidth. A speaker is a different animal with no requirement for pre-limiting the bandwidth of what goes to it.

Even in sound reproduction (speaker and rooms) impulse graphs are misunderstood and misinterpreted. I won't get into it now but will emphasize again that notions of timing/phase that audiophiles have is almost entirely incorrect. Do not fall for any of it without controlled testing.
How are acoustical impulse graphs misunderstood and misinterpreted? I've always assumed that everyone used the same simple criteria -- keeping early reflections 15 or preferably 20 dB down out to 20 ms or so, etc. This comes out of basic research, as I'm sure you know.

Well, yes, a DAC does have to have a bandwidth limited signal input to it, but I'm not sure how that's germane to the issue here. ESS measured the response of a feedback loop in what (I assume is a higher order) delta-sigma DAC. But if you want to look, say, at the impulse response of a PCM reconstruction filter, it goes without saying that you'll see ringing if you don't band limit the signal.
 

amirm

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But as I think you know, there are a few people who have done exhaustive A/B comparisons, and I've been impressed that they independently hear what I do -- to me, always a sign that both of us are probably hearing something real.
You can have 1000 AB tests. If they are not controlled tests, they have zero value. I can get any audiophile to detect differences in two identical sounds. It is trivial to do. Post the documentation for a controlled test and then we can talk. Until then, it is audio folklore.

I'd have to disagree that what ESS says isn't relevant. But we're coming from different perspectives here. I'm a working engineer, or was. I've done plenty of blind tests over the years, and have a pretty good idea of what one can hear as a result. If designers waited for a blind test of every product, nothing would ever get done, equipment would never improve. I'd note for example that it was many, many years before someone successfully ABX'd high resolution audio -- and that I had long discussions in the 80's with my good friend David Smith about the work he was doing at Sony, and we discussed the very same audible differences that are being discussed and ABX'd today. Quite simply, they were aware of much that the press, the public, and even most audio engineers weren't, because they were doing the most R&D. So personally, I'm not going to write off Sony, because that's been true of just about every designer I've known over the years.
I know of David Smith's posts years back. I can tell you that they don't have any value either.

These anecdotal stories mean nothing. I have tested audiophiles and vast majority flunk an AB test of a compressed MP3 against the original. We are talking about distortions that I can easily identify yet they have no ability hear them. All of a sudden we are to believe that they can tell subtle differences in how DAC chips are implemented? No way.

I routinely hear the differences you talk about. They are as real to me as they are to you. Problem is, once I match levels and do the test blind, the differences vanish like fart in the wind. Or else I would be publishing a paper on it and become famous. :)
 

amirm

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How are acoustical impulse graphs misunderstood and misinterpreted? I've always assumed that everyone used the same simple criteria -- keeping early reflections 15 or preferably 20 dB down out to 20 ms or so, etc. This comes out of basic research, as I'm sure you know.
That is the junk acoustic science I was talking about. None of that is based on proper understanding of signal processing, or controlled listening tests. It caters to lay intuition that a reflection must be bad. That is now how to ears and a brain as Dr. Toole is fond of saying. I wrote and published an article on that: https://www.audiosciencereview.com/...ds/perceptual-effects-of-room-reflections.13/

So no, there is no "basic research" there. It was all assumptions made in pro audio years and years back, without a single controlled test to determine listener preference. Ideas based on poorly designed speakers being conflated as acoustic issues.
 

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View attachment 31129
Hello everyone, here is the long-awaited launch of our 8-channel D/A converter, the DAC8 PRO!

After the ASR review, we received a lot of questions, feedback and suggestions and so we thought it would be a big shame to miss the chance to implement some of them into the production version. In the end, it took much more time than planned so thanks everyone for the patience, continuing support and interest in our products.

Let’s dive into the feature list, starting with the most noticeable one:

More compact enclosure
The difference visible at the first sight is the more compact enclosure (448x183x50mm excl. feet), made from AW6082 aluminium alloy. This change only applies to the DAC8 PRO, not the upcoming DAC8 Stereo.

Dust-proof and spill-proof design with conductive cooling
Speaking of enclosure… we thought what other improvements could we make to increase the durability of the product. We wanted to get rid of the vents that allow dust to get trapped inside and pile up, eventually causing overheating and possibly even killing the electronics, not to mention an accidental spill of your favorite beverage. But our DAC module produce an amount of heat that needs to be taken care of. So instead of relying on convection, we have implemented a conductive cooling using a CNC-machined aluminium heatsink that transfers heat away from the DAC module to the enclosure. Additionally, the DAC8 PRO does monitor the temperature on the DAC module and will shut down in case of overheating.

View attachment 31138

Now for the electronic sweetness inside:
View attachment 31130
Our own XMOS implementation
No 3rd party modules in the DAC8 PRO! Our own XMOS-based board controlling the USB input and AES/EBU inputs is a result of our work for the last few months. It allows for a low-latency transfer, direct control over the data flow and is tightly integrated with the user interface and the DAC board. Based on a 16-core XU216 MCU, it gives us a solid foundation for future products. Huge thanks to our software team!

4xAES/EBU inputs routed to DAC and DAW + 1 AES/EBU output
In addition to the USB connectivity, 4 XLR AES/EBU connectors provide another 8 input channels. The data flow can also be routed to the DAW USB host for additional processing before looping back to the DAC. The AES frame clock is recovered by a precise receiver and the ESS’s time-domain jitter eliminator does remove any remaining jitter. The first pair of channels is available as an AES/EBU output on a dedicated connector.

All incoming AES/EBU signals are expected to come from a single source domain. The DAC8PRO is not a quad stereo DAC, but an 8-channel DAC without any ASRC. The 8 AES/EBU dataflow is reassembled bit-perfectly by the XMOS processor and passed to the Sabre chip.

Next-generation DAC board
DAC8 PRO has received a next generation of our DAC board optimized for the task, including improved power supplies and shorter signal paths. As our other products, DAC8 PRO is designed to directly drive balanced amplifier inputs.

Ability to receive firmware updates
To add new features or fix bugs, DAC8 PRO is able to receive software updates through USB using a standard DFU protocol and an utility available for Windows, Linux and MacOS.

New functions
A powerful 8x8 routing matrix is available separately for USB and AES inputs. Individual volume can be assigned to each output channel using a 32-bit Sabre volume control

Rack mounting brackets
Our custom-designed 2U rack mounting brackets come with every unit. They are equipped with a soft lining so you don't scratch your DAC8 PRO when mounting them.

Designed for reliability, handmade in Prague
With a relay-free design and just 3 large electrolytic capacitors in the power supply, DAC8 PRO is designed for a lifetime of 10+ years. The intention during the design process was also to streamline the production and allow us to make the product in more significant numbers. But we continue to handmade all the units for you in Prague.

We are looking forward to your feedback!
Really excellent. Hope the price hasn't changed. Now if you could just find a replacement DSP board for the miniDSP nanoShark.

Btw, if you do find something along those lines, are you committed to offering retrofits for any such hardware upgrades at your facility?
 

phoenixdogfan

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I do. :) What ESS says is not relevant. What they can show in controlled listening test is. And they have none.

The Sabre glare is just a fish story created online by lay people who don't have any understanding of the real audio science. Audiophiles cannot tell gross distortions in all manner of audio gear and all of a sudden they can hear some subtlety in a DAC? Not possible. I have tested and listened to 200+ DACs. There is no such thing. Please don't believe in this nonsense and let it bias you in your listening tests.


Your posts, quotes, etc. say otherwise. That is why I am responding so that we don't have myths presented as truth in audio. When you have a controlled listening test, make sure you document it fully and present it here in a separate thread. I will save you the grief and tell you that will fail in this task but it is up to you if you want to proceed anyway. :)
I have to say I've had Sabres, AKMs and Burr Brown and been completely happy with all three. I don't know why I'm not hearing Sabre glare when I use my GO1000 to drive my HD800s. I hear it's under powered, but glare? No way. This seems like audiophile hypochondria to me.
 

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You can have 1000 AB tests. If they are not controlled tests, they have zero value. I can get any audiophile to detect differences in two identical sounds. It is trivial to do. Post the documentation for a controlled test and then we can talk. Until then, it is audio folklore.


I know of David Smith's posts years back. I can tell you that they don't have any value either.

These anecdotal stories mean nothing. I have tested audiophiles and vast majority flunk an AB test of a compressed MP3 against the original. We are talking about distortions that I can easily identify yet they have no ability hear them. All of a sudden we are to believe that they can tell subtle differences in how DAC chips are implemented? No way.

I routinely hear the differences you talk about. They are as real to me as they are to you. Problem is, once I match levels and do the test blind, the differences vanish like fart in the wind. Or else I would be publishing a paper on it and become famous. :)
Oh, I agree. I've experienced that many times myself -- which is why I've learned how to listen in such a way that it's unlikely to, and then to back that up with confirmation -- preferably blind testing, but since that often can't be arranged, independent listening. If a lot of people hear something specific that I do, and it isn't a cliche like tube sound, I tend to think it's real. Or if I sit someone down who has a good ear and a familiarity with live music, and they hear the same thing I do. Hell, that's caught me in wishful thinking more than once! Then ABX testing typically bears that out, as in the benefits of higher sampling rates, being able to hear op amps in series, the audibility of crossover distortion in amplifiers, etc.

Are we talking about the same David Smith? Legendary audio engineer and AES fellow? Believe me, what David said was the opposite of worthless -- he was the best there was, a veritable encyclopedia of audio knowledge who spent half his life answering questions for other audio engineers. Sony's research and practical experience with issues such as jitter from variable pit geometry in CD's and developments like DSD contributed to much of what we take for granted. Hell, most of the DAC's we're talking about wouldn't even exist without it.

As to the tests, sure, that's up to you. I wouldn't take as gospel what a random person said online, and I wouldn't expect you to either. I tried to do some blind tests before I had to send the Okto on, but as I think I said, there wasn't time -- I'll have to wait until my unit arrives in a month or two (or so I'm told).
 

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I have to say I've had Sabres, AKMs and Burr Brown and been completely happy with all three. I don't know why I'm not hearing Sabre glare when I use my GO1000 to drive my HD800s. I hear it's under powered, but glare? No way. This seems like audiophile hypochondria to me.
What kind of music are you listening to, and on what transducers? I find that it's very obvious in comparisons of high tessitura violin and soprano. On most material I don't hear it at all.

I'm not really sure about the AKM's and Burr-Brown DAC's. I believe my Lynx e22 is AKM, but it was designed many years ago and as good as it is it isn't as good as modern DAC's (or at least DAC's that don't live in the high noise environment of a computer). So I can't really say anything about the chip. There are those who say that the difference is between multibit delta-sigma and PCM DAC's in general, but again, most of my difference is with ESS DAC's and one can't discount the effects of analog circuitry, either (e.g., I wonder about the audibility of that -80 dB 2nd and 3rd harmonic in the Yggdrasil -- among Amir's measurements, it seems the only one that might be audible).
 

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That is the junk acoustic science I was talking about. None of that is based on proper understanding of signal processing, or controlled listening tests. It caters to lay intuition that a reflection must be bad. That is now how to ears and a brain as Dr. Toole is fond of saying. I wrote and published an article on that: https://www.audiosciencereview.com/...ds/perceptual-effects-of-room-reflections.13/

So no, there is no "basic research" there. It was all assumptions made in pro audio years and years back, without a single controlled test to determine listener preference. Ideas based on poorly designed speakers being conflated as acoustic issues.
Heh, it's a good paper. I quite agree about the audibility of high frequency comb filtering, but that's old -- dare I say ancient? -- news, and psychoacoustic measurement curves take it into account.

That said, I have to agree with Ethan here (though I read only his first comment -- didn't have time to go through the thread), as do most contemporary studio designers, who build RFZ rooms that are specifically designed to meet the criteria I mentioned at the mix position.

Yes, sidewall reflections produces subjective image widening -- I'm a familiar with the research -- but early reflections also color the sound and disrupt the image, as you'll hear if you suppress them. The reason is readily apparent in this wonderful illustration from Floyd Toole's book:

Toole -- Subjective Effect of Room Reflections.jpg

So that is where the -20 dB rule of thumb comes from -- it takes us below the threshold at which the nasties of image shift and tone coloration occur, or almost. But what about the 20-25 ms criterion? Quite simply, the best concert halls have an initial time delay gap (ITGD) of from 20-25 ms, and when we hear an early room reflection before that, the brain decides that it is in a smaller space. The subjective image size becomes constrained as a result. (There are those who say that ideally the early reflections should be suppressed out to 40 ms, the point at which tone coloration gives way to spatial impression, but in practice that's hard to achieve, as it requires that the reflecting surface be about 20 feet away).

This isn't the same as saying that room reflections are bad. We know that two channel stereo requires room reflections to sound good, and Toole found that even recording engineers preferred a somewhat live acoustic when out of the studio (and having spent a lot of time in studios, I can see why). In the typical living room, we have to live with early reflections and IMO, for the most part, it's better to have them than not. But in the best listening rooms, those reflections are delayed by 20 ms or so, which unless the room is huge, requires acoustical treatment.

In practice, when you suppress early (but not late) reflections, the subjective size of the acoustical space increases, as the ITDG in the recording is not being masked by the shorter ITDG of the room, and the sound is less colored with more precise imaging. But if it can be avoided, this should not be done with excessive absorption -- you don't want the room to be as dead as a studio, and even most studios aren't designed to be completely dead -- the idea of an RFZ room is to increase the ITDG, not to suppress reverberation.

To summarize, in a good listening room:

- Initial reflections are -15 dB or preferably -20 dB until roughly 20 ms out
- Reflections have low interaural cross correlation (again, a characteristic of the finest concert halls)
- The reverberation decays smoothly and has a constant RT60 as a function of frequency

Both diffusion and absorption (along with room geometry in professional RFZ studios) are used as appropriate to achieve these goals.

So not myth at all, but solid, research-based science borne out by experience in the field, and the reason acousticians use these principles to design control rooms.
 

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ESS DAC chips are in many Pro Audio DACs though.

Benchmark, Merging, Ayre, Mytek, Apogee, MOTU, Weiss... and probably more I can't recall.

Are all those studio engineers hearing things wrong just because of the ESS DAC chip?
If you talk to pro audio engineers, they'll tell you that modern DAC's are very, very good, but don't all sound the same.

I find it a bit amusing that the audio engineers I know and have worked with are all subjectivists by the standards of some here! :) You just can't work professionally with this equipment day in and day out without becoming familiar with the differences, and if you go to a pro audio site you'll see lots of talk about them.
 

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