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Review and Measurements of PS Audio PerfectWave DirectStream DAC

tensor9

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Just curious, but did you buy it because of a demo, reviews, or the perceived rep of the company? It's a lot of money for what it does, even if it does it really well.

I bought it based off of review and perceived rep of the company. I like how they interact with their customers (for the most part). I appreciated the novelty of the design: using an output transformer as a low pass filter for a PWM stream. Turns out in practice it doesn't work so well.
 

Ron Texas

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audimus

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As Amir has mentioned in several ASR reviews, a product with a relatively poor SINAD measurement (or other measurement) may be audibly indistinguishable from a product with a "good" SINAD measurement, assuming the noise and distortion of the poorer performing product doesn't exceed audible thresholds. With that, your claim that the "correlation between these numbers and audible perception is poor and ill-defined" is simply not true. Beyond a certain "number" threshold, noise and distortion can clearly be heard. With that, I don't understand why you continue to push the narrative that there is no meaningful correlation between good measurements and good sound (or bad measurements and bad sound).

This is a rehash of the same argument. If you go low enough in numbers, you can hear it. Sure. No one disputes that. But no one has defined a threshold where it gets a pass mark because individual hearing differences do not allow for such a clean boundary. And as you go up, somewhere it becomes inaudible to anybody. Nobody knows what that minimum number is either but one can always take a safe bet by picking a number. In addition, there are multiple components going into that number. It could be audible in one component but not the other. But two similar composite numbers may be at opposite ends in those components and therefore one may be fine and the other not.

It is in this sense, the correlation between measurement and audibility is neither well defined nor correlated.

The best you can say is that at a suitably high number, the distortion and noise won’t matter to anybody and therefore there are two buckets - pass or fail with respect to that number. That is exactly why the SINAD ranking is just a measurement ranking not an audibility ranking.

When people look at Okto’s numbers and ask “does it sound as good it measures?”, then you know there is a problem with misunderstood correlation with measurement and people’s need for good audible sound rather than measurement.

However, in this particular case, the PS Audio DAC's high distortion/noise measurements indicate that the threshold of audibility of these unarguably undesirable artifacts may have been exceeded, and Amir's listening tests appear to confirm this.
Good science would require that you establish that it has indeed exceeded the audibility threshold before opining on it. Not “may have”. But since that audibility threshold itself is ill-defined the above is not a scientific statement. Confirming it with listening tests would require (1) well documented testing methodology that can be analyzed and (2) either a causal explanation or at least correlations between such audio deficiencies (clarity, stage depth, whatever you want to pick) and the actual thing measured at that level has been conclusively established via a study of units with similar measurements and units that are better in that measurement.

Anyone with some knowledge or experience in science experimentation would understand the above.

I am sympathetic to limited resources in doing so, but that is no excuse for making definitive claims.

I agree that it may not be helpful to use a "SINAD scorecard" to judge one product's supposed superiority over another product
Good, that is a start. From now on, I expect people would not use that table to make any claims about better or worse in audibility. Perhaps a revisit of the AVR threads would be in order with that in mind.

And if they do make such a determination, they would justify it with more than where it falls in the SINAD table. :)

the correlation between measurements and perceived sound quality is demonstrably valid, as long as the thresholds of audibility are taken into account.
This is a very poor use of the word correlation. Positive correlation would imply better sound quality with better numbers and negative correlation would imply the opposite. When no such established correlations exist it is said to have no correlation (zero correlation would be more stringent requiring showing that the relationship is statistically random).

The best answer you can provide is that below a certain threshold that is hard to pinpoint and varies, the measurements may indicate artifacts that are audible with no measure of how audible. Correlation is not the right word for it.
 

audimus

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I find you difficult to understand. I think you don't really understand what you're talking about or what anybody else is saying, so your points don't make sense.
There is also a third possibility, just saying in the spirit of completeness in postulating. :)
 

JohnYang1997

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Why just can't people understand???
Any price + poor performance = not recommended
Cheap + ok performance = recommend
Cheap + great performance = highly recommend
Any price + SOTA performance = highest recommendation
Meaning, if your performance is just ok not great, you can sell it cheap and we accept it. If you sell it expensively, you better lerf performance much better than the cheaper ones. Or = BS.
If you just want cd performance, apple dongle is your friend. It's good, it's competent. Why bother spending thousands for shit???
[sad face]
 

audimus

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What is all this talk about a single number? We have divided the entire range of DAC SIAND into just four buckets. Great, good, OK and poor. And that is exactly what they are.

I should have said a single composite metric.

Yes those buckets, even if a bit arbitrary, is fine for judging engineering quality. It is their suitability to indicate audible quality that is in question in the context of the discussion. People using those two qualities as synonyms is part of the problem.
 

digicidal

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Conrad Johnson used to be the other side of the AR guys in the market. No love for CJ anymore?
Plenty of love, but I find their aesthetic and machining skills to be a distant second to AR's. Plus small 2" VU vs full 15" wide edge-lit VU on glass... no comparison.
It's just occurred to me that it would probably cost more to make a convincing replica of that amp that did absolutely nothing than to make SS electronics with really good performance. Those big machined enclosures ain't cheap.
Exactly. To me it's akin to buying a guitar that Jimi Hendrix lit on fire. You could refinish it and repair it back to new... destroying the very reason for having it in the first place - or you could put it in a nice wall mount enclosure and look at it while playing a $500 guitar which would sound much better. I am not at all embarrassed about my gear fetishism - I embrace it entirely. Just because I'm perfectly happy listening to ugly gear, doesn't diminish my desire to look at and potentially own beautiful gear as well. They're completely separate (but still related) interests. I use computers and digital cameras, but I own a number of vintage (1930's era) typewriters and cameras. They're all visually appealing to me, but I wouldn't want to have to actually use them for their original intended purpose. ;)
Nothing like doing 0-120mph runs on a Dyno that can only handle 60mph.
Has anyone here heard any of the Unity Audio 'The Rock' speakers? They make pro speakers but also "hi-fi" versions that look not bad at all. <https://unityaudioproducts.co.uk/boulder-hifi.php>
I do think those look pretty good. I particularly like the fact that they have HIFI versions which are exactly the same except for this critical difference:
The Boulder features the same Tim de Paravcini amplifiers as the rest of the range. Internal wiring is by Audioquest and critical audio path components are supplied by Mundorf.
That's what I call "knowing your customer." If you don't want pointless audiophile accoutrements then we've got your speaker, if you want to pay us extra to say that you have them... we've got your speaker too. :D
 

audimus

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Why just can't people understand???
Any price + poor performance = not recommended
Cheap + ok performance = recommend
Cheap + great performance = highly recommend
Any price + SOTA performance = highest recommendation
Meaning, if your performance is just ok not great, you can sell it cheap and we accept it. If you sell it expensively, you better lerf performance much better than the cheaper ones. Or = BS.
If you just want cd performance, apple dongle is your friend. It's good, it's competent. Why bother spending thousands for shit???
[sad face]

Why can’t people understand engineering quality performance is not a synonym for audibility quality performance to not conflate the two and be more precise in what they say?

Ok, I am ducking out before rotten eggs and tomatoes head my way. :)
 

FrantzM

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Hi

Coming to term with the fact that electronics are essentially transparent (note the adverb) is a shock to many. It is deeply unsettling, after a life chasing the last iota in audio reproduction "perfection" at an oncreasingly dearer ... Such realization seems to suggest the end of the road, the end of a hobby, the end of the Hunt. These hurt the High End Industry,predicated on "more Better every time it gets more Expensive”:. pardon the violence on Shakespeare mother tongue :).
Thing is this myth of continuous betterment has brought considerable profit to many. When a person has audacity and knowledge to backup his refutation of the status quo it can only be met with vehemence, especially when arguments are missing .. Emotions are the last resort.
A bit OT
Currently listening to least expensive and much better DAC and Headphones Amplifier combo, I have ever purchased .. The ASR Special (Khardas Tone Board + JDS Labs Atom).. $200 total should not sound that good and/or drive any non_ESL headphones that well ... And to think it is superior in all objective aspects to this thing hing costing ... 30 times more ... I mean PEOPLE!! 30 Times more , yet inferior in all objective aspects ... Thanks Amir. The revolution is under way .. They are taking notice... Wow!!!
 

GrimSurfer

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This is a rehash of the same argument. If you go low enough in numbers, you can hear it. Sure. No one disputes that. But no one has defined a threshold where it gets a pass mark because individual hearing differences do not allow for such a clean boundary. And as you go up, somewhere it becomes inaudible to anybody. Nobody knows what that minimum number is either but one can always take a safe bet by picking a number. In addition, there are multiple components going into that number. It could be audible in one component but not the other. But two similar composite numbers may be at opposite ends in those components and therefore one may be fine and the other not.

It is in this sense, the correlation between measurement and audibility is neither well defined nor correlated.

The best you can say is that at a suitably high number, the distortion and noise won’t matter to anybody and therefore there are two buckets - pass or fail with respect to that number. That is exactly why the SINAD ranking is just a measurement ranking not an audibility ranking.

When people look at Okto’s numbers and ask “does it sound as good it measures?”, then you know there is a problem with misunderstood correlation with measurement and people’s need for good audible sound rather than measurement.


Good science would require that you establish that it has indeed exceeded the audibility threshold before opining on it. Not “may have”. But since that audibility threshold itself is ill-defined the above is not a scientific statement. Confirming it with listening tests would require (1) well documented testing methodology that can be analyzed and (2) either a causal explanation or at least correlations between such audio deficiencies (clarity, stage depth, whatever you want to pick) and the actual thing measured at that level has been conclusively established via a study of units with similar measurements and units that are better in that measurement.

Anyone with some knowledge or experience in science experimentation would understand the above.

I am sympathetic to limited resources in doing so, but that is no excuse for making definitive claims.


Good, that is a start. From now on, I expect people would not use that table to make any claims about better or worse in audibility. Perhaps a revisit of the AVR threads would be in order with that in mind.

And if they do make such a determination, they would justify it with more than where it falls in the SINAD table. :)


This is a very poor use of the word correlation. Positive correlation would imply better sound quality with better numbers and negative correlation would imply the opposite. When no such established correlations exist it is said to have no correlation (zero correlation would be more stringent requiring showing that the relationship is statistically random).

The best answer you can provide is that below a certain threshold that is hard to pinpoint and varies, the measurements may indicate artifacts that are audible with no measure of how audible. Correlation is not the right word for it.

I think you're stirring the pot a bit too hard.

You appear to be basing your thesis on one measure of one metric. Just for indulgence sake, let's address this.

It would be fallacious to pick the highest SINAD level at which things become inaudible. People have different hearing. They listen to music at different level. They do so in different spaces, using more than a DAC.

BUT, we can say with the weight of medical science behind us that human hearing has a limit of -118 dB. Does that apply to very single person? Who can say. But it has been accepted in science which has undergone a very high degree of peer review. So in the absence of better info, it's a reasonable place to start.

Now this raises a legitimate discussion on whether or not noise and distortion is detectable by human hearing in normal listening conditions. Normal is a broad and undefined term, so it is wise to use a standard definition. That is, whether you like it or not is 85 dB and is sometimes expressed as 0 dB because it serves as a reference point. The 0 dB reference point isn't arbitrary... it is the threshold between the highest spl of audible broadband sound that people can listen continuously to without suffering some form of permanent hearing damage.

If I understand this correctly, an unimpaired human should be able detect sound at -118 dB from the reference point. How much distortion? That is another matter entirely because it is not simply an issue of spl but of frequency, harmonics, and percentages. It is highly dependent on space too.

How much does masking play a role? What about reinforcement? Depends on other gear being used, none of which Amir can "see" because he doesn't dictate the terms under which everyone on planet earth listens. In other words, it is an uncontrollable variable so shouldn't play any definitive role in his assessment. This is something I will get back to at the end of my post.

Even considering all of this, medical science tells us that sounds occurring at -119 dB are technically inaudible by the vast majority human beings. This is something eminently useful to consider, and a point I will use at the end of this post.

Psychoacoustics holds different views and, based on your posts, it appears you are a fan. But psychoacoustics remains a developing field. So much so that there is considerable debate between psychoacousticians on the levels at which sound can be perceived (as opposed to heard, because psycoacousticians have been unable to demonstrate, in any scientifically accepted manner, that human hearing extends beyond -118 dB). In other words, psychoacusticians are not in agreement on the fundamentals of the field.

You appear fixated on SINAD. This isn't because you don't understand what I've written above. I think you have an excellent grasp of audio. Instead, I see your quest for a single answer as an ideological pursuit in which your goal is to redefine the significance of established SINAD thresholds. One of your methods of discussion is symantics, which I can appreciate were it not for the fact that all such discussions usually start nowhere and end nowhere (that is their nature, after all).

So I think you might be missing (or dismissing) the essence of standards. They are not absolutes but benchmarks. They confer no meaning on their own but can be used to derive great meaning when combined with other data. Because that other data can affect the outcome greatly, it can only be resolved on a case by case basis. When we go down this path, the symanticist then says "yeah but", leading the discussion on another tangent leading to nowhere.

This doesn't achieve anything other than to serve as a get out of jail free card to expensive, audiophile shite that trades opportunities for high performance for the certainty of high profit (assuming there's any engineering competence involved in the endeavour).

The great thing is that Amir makes enough of his measurements (of different aspects of performance) available. This allows users to independently draw their own conclusions, using (among other things) the variables of their listening conditions and capacities.

So nobody is holding a gun to your head, or mine, forcing us to accept Amir's net assessment.
 
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alex1berg

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It's worse in my house. AC running 6 months a year, forced air hear for 3. Nearby rail and truck traffic. Crazy wife.

The real question is why can a "respected manufacturer" make a $6k dac that measures like a motherboard Realtek chip and get glowing reviews for it?
The crazy wife hit home and had me laughing till I couldn't breathe.
 

restorer-john

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Incompetence, arrogance, or criminality? Which to choose from?

Choose the one that doesn't get you sued for libel/defamation.

Many aspersions have been cast against individuals in this publicly viewable thread by a whole lot of members. It's actually an ugly, pile-on, lynch-mob mentality and I hope we do better in the future.

In the scheme of things, it's one D/A converter, from one company, that was discovered to not perform terribly well. Whoopee. Not exactly curing cancer here are we? Just because a designer or owner/partner of the company has a small online presence and so does Amir, it's OK to behave like a bunch of kids in a school-yard fight? Reminds me of this scene:

1569548497248.png
 
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alex1berg

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Why can’t people understand engineering quality performance is not a synonym for audibility quality performance to not conflate the two and be more precise in what they say?

Ok, I am ducking out before rotten eggs and tomatoes head my way. :)
Goodbye
 

Sal1950

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To be honest, for most people, the CD arrival was a stunning improvement. It wasn't even progressive like the arrival of digital photography, just sudden, and quite a shock. Also, since Sony and Philips were the drivers and volume ramped up quickly, prices fell drastically in a year or so. I'd say that, in a way, this was the first time consumers saw a huge improvement compared to what they had and an amazing price drop in a bit more than a year.
Exactly, that's how it was for me after almost 40 years of wrestling with all the physical, technical, and convenience issues with vinyl. To this day I still can't understand the fad of vinyl resurgence. BLAH.. LOL
 

Rja4000

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behave like a bunch of kids in a school-yard fight
I have this feeling too and I don't like it either.

It's like there are several parallel discussions in this thread:
One is about measurements, their relevance and the counter arguments from the manufacturer - if any.

The other one is, at best, noise, or rather very high level odd distortion, which sounds bad...
Personal attacks are, for me, like hard digital clipping. I can't listen to that for even a short time.

I don't want to give lesson to anyone. Just to describe how I feel with this.
On top of thinking this is highly counter-productive for the announced goal of being influential.
Goal that I find very respectable.
 
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GrimSurfer

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Exactly, that's how it was for me after almost 40 years of wrestling with all the physical, technical, and convenience issues with vinyl. To this day I still can't understand the fad of vinyl resurgence. BLAH.. LOL

I think that many of those who lived through the vinyl and tape (8 track, cassette, R2R) era recognized greatness when digital music arrived, first as DAT followed by LaserDisc, CD and lossless digital.
 
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Rja4000

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It's like there are several parallel discussions in this thread:
One is about measurements, their relevance and the counter arguments from the manufacturer - if any.
Just want to add:
This discussion -and 'discussion' means that there are different opinions- is healthy for any kind of scientific quest.
In fact it's even vital.

So we should never allow that counter-arguments are forced quiet by any other method than explanation and evidences.
And no, we don't need to all agree at the end.
Any other method is a negation of what we say we do here, in my opinion.

Ok, we all know world is not ideal and distortion-less...
Fortunately :)
 
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digicidal

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So I think you might be missing (or dismissing) the essence of standards. They are not absolutes but benchmarks. They confer no meaning on their own but can be used to derive great meaning when combined with other data. Because that other data can affect the outcome greatly, it can only be resolved on a case by case basis. When we go down this path, the symanticist then says "yeah but", leading the discussion on another tangent leading to nowhere.

Yeah, but... (sorry I had to). :p In many cases there may be one or more aspects of a given application of science that cannot be simply measured and compared - either because they are subjective by definition, or because the current research/technology is inadequate to completely describe the inherent variables. Luckily in audio reproduction, there is almost nothing left in the second category. Despite this, there is enough in the former to keep shillers shilling and enthusiasts arguing for at least my lifetime - if not forever.

The great thing about objective analysis is that there isn't an inherent emotional component to be considered. Even if @amirm went into every review with a bias for/against a particular device... the AP555x isn't aware of this. It simply receives a signal and measures it. Where the emotions come into play is after those results are published. To a limited extent perhaps, also in the words used to describe them - although I find Amir to be very fair in semantics, for the most part.

The key point (for me at least) is that regardless of whether SINAD is the best single metric for comparison, it's definitely one of the more important ones - if the signal is buried in noise/harmonics... then it's definitely not the original signal any longer. Thankfully, that's not the only metric provided, just the one used for graphical comparison to like devices. However, with DACs in particular, what other than source-to-output accuracy should be considered? I certainly can't think of anything. A DAC shouldn't be "making sound" (by definition) it should simply be converting it... so if it is adding something - you have to consider why it is. There's really only two options - accidental additions because of poor engineering/component selection - or deliberate modification to create a sound that is not representative of the source material. Sure filters need to be applied, but not to add anything - they're necessary to eliminate what would otherwise be added.

If PS Audio created a DAC Buffer device, which they marketed like:
Our device, inserted between the DAC and amplification stages of your system, will soften the overly-analytical sound of digital audio by inducing a low-level of noise into the signal chain much like a tube pre-amp would. Those overly-bright or harsh digital files will now sound much closer to vinyl or analog tape with a reduction of dynamic range and emphasis of pleasing 3rd harmonic distortion.
Not only would I not find fault with it (unless it actually measured as transparent in which case that would be deceptive) - I'd congratulate those that were loving their noisier audio again... I just wouldn't join them. ;)
 

Sal1950

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I tend to agree with Krunok, esthetics carry some importance for me. I gladly pay extra for a nice wood finish and grill cloth on the various Pro monitors, they are butt ugly. Wouldn't have to cost a fortune. My HSU's look handsome in their Rosenut finish. My room size, etc; restrict me to stand monitors, but why do they all have to be fugly?
In studios they actually look ok, but as soon as you put them in a room they turn that butt ugly face. :D
Ooo Ooo, Look what I just found! Don't want to take this thread too off topic so I started a new thread.
JBL has made the 705/8's purdy, passive, and bigger.
https://www.audiosciencereview.com/forum/index.php?threads/new-jbl-and-revel-speaker-lines.9162/

JBL-1.jpg
 
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