All the best,
I'm afraid that while I see where you are going, there's a lot of yelling that obfuscates and in some ways goes counter to your argument.
If I read it as written, it seems you are saying that caps and coils introduce errors and we need to be OK with that.
Impulse responses are digital fabrications, they have no pre or post ringing. but you are insisting there is. I think to make your argument you need to simplify it a bit.
Also, regardless of up or oversampling, all measurements I've seen still display "ringing." A better argument might e that this digital impulse response is not possible in nature.
I think your overall message is that a perfect, 1 sample wide impulse is outside the boundaries of actual sounds and that within the boundaries of what a natural impulse response would look like, there's no error. Is that true, or am I still misreading?
Not sure I agree with all the statements by the OP but the best type filters have long been known as linear phase - these filters preserve the phase relationship between the various frequencies in the audio signal - this is important for correct timbre. Anything else is wrong. So yes MQA is a significant step backwards for audiophiles - the cure to fix pre-ringing is far worse than any perceived or invented problem from pre-ringing in playback.
Of course some extreme Q filters used in mix and mastering can create pre-ringing effects that are audible. In that case, the audio is highly filtered and over produced to begin with. Generally a filter designed to correct this pre ringing is only going to make the audio worse - especially if applied to the entire signal rather than just the instrument that is of concern. Most often this preringing occurs on snare drums where a lot of compression and gating is applied - in this case a minimum phase filter in the studio protools world may be preferable to linear phase - however this will change the timbre of the snare.
cj1965 "There's been a lot of misinformed babble... and similar pseudo science clap trap...Newsflash folks - it's a scam...So effectively the entire debate about ringing in digital audio is a misnomer - a hoax... Any audio system that eliminates or significantly alters this pre/post ringing present in the signal that is fed to it is not truly "high fidelity" and is thus bandwidth limited."
Well it is certainly easily proven that every audio system is "bandwidth limited" so I am not sure what your post has done to compensate for the babble and clap trap you complain about with such such vociferousness also just because you find fault with a specific audio process, protocol or topology does not make it a "hoax" or voodoo or snakeoil.
In the real world, any pre or post ringing associated with digital pulses in pulse code and delta sigma converters is at such a low level and frequency outside the working bandwidth of the circuit as to be of no consequence whatsoever. The comparators, op amps and output filters used are not sensitive in any meaningful way to any ringing unless you are feeding the circuit a Dirac Delta type or Impulse response signal. In that case, yes - low level pre and post ringing could be high enough in amplitude and low enough in frequency to register in a typical converter output. In the real world, however, no such signal containing extreme bandwidth and amplitude will ever be encountered with normal signals. Again, the issue of pre and post ringing is a red herring - a hoax propagated to make a bogus sales pitch for a solution in search of a problem. The manner in which normal signals are digitally deconstructed and reconstructed prevents low level switching noise in digital circuits from becoming audible.
There are lots of things wrong with Redbook CD including but not limited to scattered background laser light getting into the photodetector, the stubborn vulnerablity of CDs to vibration of all types, especially seismic vibration, CD wobble during play as a result of out of round discs, the susceptibility of CDs to static electric charge and the susceptibility of electronics in CD players to Magnetic fields and RF interference. Other than that, no problem! Perfect Sound Forever! 😛
The ancient Benz wagon I've had for many years has a six cd changer in it. I has traveled over some of the roughest roads in New England and has never missed a beat. Perhaps I should drive it out to California and wait for an earthquake. Maybe then I'll witness this "stubborn vulnerability , especially to seismic vibration" that you speak of..As for the litany of other ills you mentioned, I guess I'm lucky to have never experienced any of those problems. I must be one very lucky guy never to have seen evidence of pre or post ringing originating from digital audio circuitry or any of the maladies you speak of....But for you, my friend, there's always vinyl ...
" I think MQA will just give the government a cut of the profits... " - jl35
If you want to know who is being paid off, look for the loudest supporters of this "new innovative technology" which features claims of "improvement" that cannot be tested for or measured. You will also find that these loud supporters are the quietest among the crowd of "faithful" when it comes to discussing the proprietary and security control aspects which represent the downside for consumers.
Cj1965. I think you’re on the money all round. The military build up is scary-and wastes a lot of resources. But recent wars have improved 1st aid knowledge and techniques-so they can argue those benefits.. The major record company investors “partners” must be licking their lips thinking of reissuing everything since Al Jolson- all ‘new n improved’
More propaganda from a truther. Why do you need instruments when you have 2 ears to hear if it sounds good or not.
This thread is no different than a vinyl addict claiming analog is better while we know the issues with analog.
I have good equipment to hear what I think the best formats are: vinyl, MQA, dsd, hi res, redbook. I don’t need somebody that claims to know something to persuade me 1 way or another.
" More propaganda from a truther. Why do you need instruments when you have 2 ears to hear if it sounds good or not. " - rbstehno
Typical misinformed "audiophile" response to any objective fact finding.
It's one thing for a manufacturer to buddy up with a few audiophile press "journalists" - offering practically free equipment, tickets to major sporting events, or just simply buying large amounts of advertising from their "honest, trustworthy, and principled" employer in order to get favorable, totally subjective "press" to help move product. The potential negative impact to consumers who might wind up buying a totally over hyped product is going to be limited. You simply can't fool everyone all of the time. MQA, however, represents a different thing entirely. IT IS A PROPOSED STANDARD FOR AN ENTIRE INDUSTRY. So the same old tired stupid behavior that might be tolerated regarding audiophiles and their complete adherence to the value of subjective criteria over objective, provable criteria won't cut it. Any time an industry standard is proposed, it is appropriate and actually ENTIRELY NECESSARY for objective criteria to be provided that establishes concrete, measurable characteristics with which "qualifying products" can be measured against.The problems with MQA is that it doesn't provided any concrete characteristics or criteria that can be measured to allow anyone to prove that a particular quality standard is being met. THE ENTIRE THING IS SHROUDED IN MYSTERY, DOUBLE SPEAK, AND THE USUAL "VEILS HAVE BEEN LIFTED" CLAIMS you sometimes get with manufacturers pushing new products. And the justification for all the secrecy surrounding what it does and how it does it boils down to intellectual property claims. THIS IS WHAT PARTICULARLY STINKS ABOUT MQA. THE ONLY NOVEL OR PATENT WORTHY ASPECT TO IT PERTAINS TO THE SECURITY/ENCRYPTION FEATURES BUILT IN - AND THAT ASPECT WASN'T EVEN CREATED BY STUART ET AL., ITS WAS SUBBED OUT TO ANOTHER COMPANY!
MQA ... IS A PROPOSED STANDARD FOR AN ENTIRE INDUSTRY.Yes, we understand that. Shouting is not necessary.
So the same old tired stupid behavior that might be tolerated regarding audiophiles and their complete adherence to the value of subjective criteria over objective, provable criteria won't cut it.Why so angry?
THE ENTIRE THING IS SHROUDED IN MYSTERY, DOUBLE SPEAK, AND THE USUAL "VEILS HAVE BEEN LIFTED" CLAIMS ...I'm beginning to think you don't care for MQA.
THIS IS WHAT PARTICULARLY STINKS ABOUT MQA. THE ONLY NOVEL OR PATENT WORTHY ASPECT TO IT PERTAINS TO THE SECURITY/ENCRYPTION FEATURES BUILT IN ...Okay, you don't like MQA. I'm not much interested in it, either. It's just a puzzle that you'll go to such lengths - the ALLCAPS, the insults - to oppose it. It suggests you have as much at stake as those you criticize.
"More propaganda from a truther"
Did you say insults?
If people think they can contribute to a thread like this with ignorant insults and not get them thrown back in their face, they're delusional. It's' not a personal attack to acknowledge a basic simple fact: A high percentage of audiophiles completely disregard the value of ANY objective criteria when it comes to the sound reproduction industry. That is simply not acceptable or even rational. For those who are so inclined, there are plenty of "vote for or against" threads in which to participate. This is not one of them.
With regard to the use of CAPS. Unfortunately, a lot of people don't read or attempt to reasonably comprehend others comments before putting forth stupid, misinformed attacks or snarky comments to help boost their fragile egos. CAPS are sometimes appropriate to get some individuals to actually pay attention to SALIENT FACTS.
If people think they can contribute to a thread like this with ignorant insults and not get them thrown back in their face, they're delusionalPlease don't threaten contributors here. Please.
A high percentage of audiophiles completely disregard the value of ANY objective criteria when it comes to the sound reproduction industry. That is simply not acceptableIf you find behavior here unacceptable, please alert the moderators rather than threaten contributors here.
With regard to the use of CAPS. Unfortunately, a lot of people don't read or attempt to reasonably comprehend others comments before putting forth stupid, misinformed attacks or snarky comments to help boost their fragile egos.Please, stop with the insults and the threats.
cj1965, Please calm down. If MQA is a hoax, it will not become the industry standard. So far it is only being used to stream hi-res on Tidal. Tidal always offers the albums it has encoded with MQA in 16/44.1 also.
I don’t know how familiar you are with this forum, but we try to keep
discussion low key and friendly. There is another audio forum known for angry arguments, insults and hostility. If you prefer to express yourself that way, I think you would find that forum suits that style better.
So go ahead and present your arguments against MQA, but without the anger towards people who haven’t come to the same conclusion.
I'm very calm. Use of capitals doesn't mean I'm not very calm. I'm not sure how to highlight or boldface anything for emphasis using this interface. Unlike most of the participants here, I don't bother posting to such forums very often. I just don't have the time to amass 5 or 6 thousands posts on an audio forum so I'm a little green when it comes to finding features like emojis or text editing buttons.
As for anger or hostility towards others - if someone pops into this or any other thread with an insulting comment like:
you're a "truther" spreading propaganda - without anything to back up this statement or factually contradict anything presented in the thread, they will be responded to in kind (see above comment from rbstehno). Essentially all of that users comment was personal attack and nothing was focused on the actual information presented in this thread which centers around ignorance of what a Dirac Delta or Impulse function really is. Whether or not you or others have thin skin and don't like it when someone points out the complete lack of knowledge or understanding on the part of members talking about "pre ring" - I can't help that. The facts are what they are. Impulse signals are what they are - special signals that have absolutely nothing to do with what audio circuitry deals with on a regular basis.
All forums such as this strongly encourage participants to focus on the subject matter and avoid attacking the messengers. Just because you don't like the message, it doesn't give you or rbstehno the right to personally attack another member's character with unsubstantiated "truther" or "propagandist" labels.
Your point that preringing and postringing do not exist is not generally accepted as fact among the people who design and build audio equipment. If you want to present that opinion to us, fine, but to say it's fact and that anyone who doesn't agree is ignorant is not helpful to your cause. I'm just suggesting that you lower the intensity of your posts a little. We don't need an MQA war here. As I said, there are forums where such a war would be welcome.
You made some very good salient and interesting points that had me reading deeper.
BUT( sorry could not resist)
The use of caps to "shout" and your general "take no prisoners" attitude will not win you any favours here. Members will unfortunately soon look past the meat of this thread and just concentrate on the flesh (insults, attitude, shouting etc)
That will not help your cause of the one of this thread one little bit and that would be a shame.
It is hard I know when one feels they are being personally attacked but may I suggest a modicum of patience?
" Your point that preringing and postringing do not exist is not generally accepted as fact among the people who design and build audio equipment. If you want to present that opinion to us, fine, but to say it's fact and that anyone who doesn't agree is ignorant is not helpful to your cause. I'm just suggesting that you lower the intensity of your posts a little. We don't need an MQA war here. As I said, there are forums where such a war would be welcome." - tomcy6
Please cite some examples of "people who design and build audio equipment" who claim that music reproduction involves "pre and post ring" signals. I use impulse tests on a daily basis. I would like to see evidence of ultra broad band high intensity, ultra short duration peaks in music or any other signal source to back up what you appear to be saying. If you read the thread carefully, you will find that no one is saying pre and post impulse ripple doesn't exist. What you will find if you actually read the beginning of the thread is that these phenomenon only exist in circuits that utilize extreme attenuation of signals. Filter theory is very old. There are no special new filters that violate the laws of physics. Every steep filter produces oscillations that can easily be calculated for mathematically in the transfer function and represented in a Bode plot displaying stability or lack thereof. The problem with the entire foolish MQA promotional exercise is that a handful of "Industry people" are using impulse response data to infer that such signals are routinely present in music and their special characteristics (pre/post ripple) must somehow be dealt with. This is a complete farce that exposes widespread ignorance in the "audiophile" community - or at least that subset of the community that embraces ridiculous postulations about impulse signals that aren't true for the majority of music data fed to digital circuits.
Again, if you know anyone in the industry who can demonstrate that pre and post impulse ripple is encountered in music playback, I for one would like to see evidence of it. The anecdotal " I know some people" isn't sufficient. Evidence is required. If you want further citations for what an impulse signal is, I can provide links and you can actually generate them yourself using readily available software and a modest equipment setup. You can contrast the signals you produce with that of sharp pulses produced by a square wave generator - another signal type that doesn't exist in the real world of music but is used for equipment testing nonetheless.
There's an old saying about "a little information" being dangerous. That is precisely what is going on with MQA and signal ringing. The folks that are being misguided know just enough about the subject matter with which to make fools of themselves. Take the time to at least generate some impulse response signals yourself before you go on an internet forum to "educate" others about it. I have done it. You can too.
As posted above, there has lots of positive and negative comments on Audiogon about MQA coded albums. Of course, everyone is entitled to their own opinion that I enjoy reading. I listen to Tidal MQA coded albums since I feel they sound slightly better (sometimes) than regular albums. The music seems clearer and with less background noise.
I do NOT LIKE the Audio Manufacturers having to pay for the MQA license and noticed that some support this extra cost and many others do not. In addition, I know that some people “believe that supporting MQA means handing over the entire recording industry to an external standards organization”. If this statement is true (is it?), it is also a concern to me.
I own the Aurender N10 Music Server (it decodes the first MQA layer) and has 10,000+ MQA Coded albums from Tidal that I enjoy. However, I would NOT PAY extra for MQA coded albums. I also know that some Manufacturers want nothing to do with the MQA coding process.
I continue to believe we have too many audio formats that make it very confusing for people new to audio and maybe everyone else (such as who does the unfolding of the different MQA layers?). Some DAC's support MQA and many others do not and will NOT. There is much confusion, concern and debate around MQA coded albums, so I am waiting to see what happens.
Charles Hansen of Ayre Acoustics (now deceased, R.I.P.) and many other audio manufacturers use Minimum Phase filters in their digital components. It is my understanding that the purpose of these filters is to eliminate preringing. I know very little about electronics so I may be wrong about that. With that, I’m out of this discussion.
Here is what Charles described as one of his accomplishments in audio design:
"World’s first disc players to provide user-selectable “Minimum Phase” digital filter responses, including both “slow roll-off” algorithm with improved transient response and “apodizing” algorithm for removal of ringing from digital filters used to produce the disc."
Read more at https://www.audiostream.com/content/qa-charles-hansen-ayre-acoustics#8mhJtBVPIS8iPIDQ.99
cj1965"cite some examples of "people who design and build audio equipment" who claim that music reproduction involves "pre and post ring" signals. I use impulse tests on a daily basis. I would like to see evidence..."
hey cj1965 here’s you’re very answer to someone else who asked for some proof. Do you recognize this???
"cj1965Oh puhleeeeeze. Spend five minutes of your time Googling...Nobody is going to waste time giving you proof of the obvious. If you’re that lazy...don’t expect any of us to serve it up to you on a silver platter.
So it is only fair to now ask you to Google for yourself!
" Charles Hansen of Ayre Acoustics and many other audio manufacturers use Minimum Phase filters in their digital components. It is my understanding that the purpose of these filters is to eliminate preringing. I know very little about electronics so I may be wrong about that. With that, I'm out of this discussion. " - tomcy6
Ok. Let's be clear about what minimum phase filters are. By definition, a minimum phase filter is a filter that remains causal and stable when used in a linear, time invariant system. All that really means is that phase and gain changes cannot result in oscillation (unstable). For this to occur, the poles and zeros of the transfer function plot have to stay inside the unit circle. A common example of violation of this characteristic happens when an amplifier's overall phase shift is 180 degrees at unity gain. Under those circumstances, a typical feedback amplifier will oscillate.
In terms of filters, it really has nothing to do with impulse response. As noted previously, to generate a very rapidly increasing and rapidly decreasing voltage spike in a linear, time invariant system - requires and extremely sharp (steep) filter. That's where the ringing (instability) comes in. A minimum phase filter in Charlie's case is simply a gradual rolloff (low phase shift with frequency) filter that is causal and stable - minimum phase. We are talking apples and oranges here. There is absolutely nothing whatsoever about an impulse signal that is "minimum phase".
The problem with your suggestion is that it is based on a faulty premise. The Audiophile press's push to back MQA is "common knowledge" as a quick 5 minute Google search will reveal. The problem with the MQA pre ring post ring hoax is that a "common misconception" nurtured by a handful of industry people exists with respect to the pertinence of pre ring/post ring phenomena in digital audio circuits. There aren't enough people exposing the common misconception promoted by Bob Stuart in forums like this to counter the smoke screen. However, the "common knowledge" of MQA promotion in the audiophile press - that's easy to find. You don't have to corner an electrical engineer or delve into signal mathematics on wikipedia to figure that out. BIG DIFFERENCE, my friend.
cj1965"The Audiophile press's push to back MQA is "common knowledge" as a quick 5 minute Google search will reveal. The problem with the MQA pre ring post ring hoax is that a "common misconception" nurtured by a handful of industry people exists with respect to..."
I understand completely there is one level of proof required for one thing and another level of proofs required for another and in BOTH cases you don't provide the proof but demand others do it for you and insult those who question your motives which you still have not revealed so yes I can see why you say faulty premise!
Good to see people coming around to the dog and pony show
As an engineer I have been very concerned about a world of MQA audio, marketed as equal to or better than the master.
It's not. Equal. Or Better. At all. Period.
Making a playback system is a fine form of creativity for the audiophile, and preference for mp3s over 24 bits has happened in blind tests. Preference is not important with MQA, all that matters is the integrity of the master.
With all the techno babble being pushed to and fro regarding MQA, the bottom line is that MQA uses a lossy compression system and once lost ...... 'it ain't coming back'! Think about it! Look what MP3 has done to sound quality. Unless you can provide an audio carrier system that can retrieve musical information in it's entirety 'without loss', we will always be bombarded with claims of a fix. MQA is another form of resolution strangulation. ..... 'We'll do it in a nice way and it won't hurt a bit!'
As we all know, the present times show that every coffee table round is filled with the "real experts". And that the so-called "elite" (be it political, technical or economical) is corrupt and all these are false experts.
Leaving this premise beside:
Reading through previous work of Craven, and some papers of (yes, indeed!) Bob Stuart, everybody could see that both have a very high level of mathematical and engineering skills and training, besides original thinking.
The way this expertise is simply thrown into the wind in these discussions, flooded by arguments that are, put in diplomatical words, two or three floors below the level set by Craven and Stuarts, makes me cringe!
However... a few critical words towards MQA first:
When the Sony PCM recorder was first introduced in the beginning of the 80's, engineer K.L. Breh of "HiFi Stereophonie" measured the Sony PCM machine vs. a tape recoder run at different speeds.It was obvious by looking at the signals after passing the *complete* recording/replay chain, that the PCM recorder had far worse impulse response (then induced by the analogue filtering, the Sony wasn't oversampling digitally).
- I miss such a complete measurement, including frequency response, distortion, impulse response and aliasing artefacts of a complete MQA chain. This would clear up many slightly (at best) "foggy claims" of MQA.
Where are these complete measurements, which are not that complicated to do for a professional reviewer?
- That MQA "messes" with aliasing criteria is something that silently is distilling out of this fog.
- Pretending that there is no aliasing artefact, because there is no information in the frequency range close to the sampling frequency, which would cause aliasing, would make the whole HighRez issue a moot point - if it is, or if it would be true. (To which point I want take a position in this discussion).
If there is no signal that can cause aliasing, the sampling frequency is unnecessarily elevated, no need for HighRez.
- The impulse response that "nicely" shows the FIR filter coefficients of a digital filter (and or the type of used analogue post-DAC filters) generating ringing is an artificial signal, reproduced by playing only half of the recording chain: DA only.
It would look quite different if looped through the complete AD/DA chain.
The ringing seen can't be triggered by a correctly lowpass filtered PCM recorded impulse.It shows - as a semi-abstract picture - what filters are used.
However... a few points about MQA are IMO brillant:
- the "information density" in the range above 22kHz is *way* below that in the midrange or audio range. To double, quadruple or "octuple" (;-) the sampling rate for *objecively* (measured and sampled) very small amounts of information is not elegant. It is in a certain way an idiocy.Thinking about how to "underfeed" this information into normally sampled digital files is a brillant idea (IMO).
- Contrary to many here on this thread I doubt that the "lost bits" below bit 18 or 19 and below the already nicely sampled noise from the recording chain are audible at all. 20 Bit conversion is all we need for audio. 32 bit resolution is "fake news" or good marketing... :-)
DSD has a lot of fake advantages that are no less marketing driven, like "analogue-like" signal handling (with very high order noise shaping processes necessary not quite true), and has drabacks at least in DSD 64 format, and the other formats are increasingly wasting huge amounts of storage.
The proprietary MQA mastering and decoding process is a thing to critically reflect about but IMO also maybe nice to have – if every other question is openly answered. And if the majority of the claims and promises are kept.Which I will not exclude at this moment.Throwing MQA into the garbage could be a missed opportunity which future generations might be sad about, at least from a quality point of view.
No idea what this fellow is going on about...but I do have a lot of recording studio as a musician experience. I have A/B’d MQA vs non MQA countless times on my two high end audiophile systems at home. Any MQA version only sounds to my ears as a slightly different studio mix from the previously available version. It never sounds better ... or worse.
" The way this expertise is simply thrown into the wind in these discussions, flooded by arguments that are, put in diplomatical words, two or three floors below the level set by Craven and Stuarts, makes me cringe! " - pegasus
Really? Two or three floors below level set by Craven?
Just another useless "audiophile" comment aimed at attacking the messenger's credibility without any factual or objective basis whatsoever. This thread is very straight forward and simple - Craven et al. are using a phony argument about impulse response ripple to try to insinuate that such a phenomenon is present in everyday digital sound recordings. It is very clear from the Stereophile impulse response graphs that MQA is doing nothing more than adding dither noise to hide the pre and post ripple associated with the impulse input signal. Additionally, the "origami fold, unfold, deblurr " BS does nothing but add phase delay (distortion) to the primary impulse peak (see negative going pulse just after MQA enabled DAC response that doesn't exist in the non MQA Brooklyn DAC response).
If you have anything to say about the technical facts presented here, please direct your comments to those facts - possibly citing some facts of your own. Otherwise, spare us the "Mr. Craven et al are several levels more brilliant than anyone who is participating here in this thread". Your unsubstantiated insults are not welcome. Play the ball - not the man.
As for critiques of the original Sony/Philips PCM approach with steep cut off filters 35 years ago - no duh. It was clearly pointed out at the beginning of this thread that oversampling solved the "ringing problem" in digital audio before many of the readers who come here were even born. And no, Mr. Craven's "appetizing" filter (pun intended) doesn't resolve the distortion problems created in those early recordings.
There is no need for any of Mr. Craven's security encryption schemes disguised as sonic improvements. The only potential need in the industry that exists is to take the current lossless standard and make it more efficient - some scheme to detect the dynamic envelope of every file that is to be streamed and apply only the bit depth necessary to transmit the particular file. It's a very simple concept but because it doesn't involve "protecting the family jewels" and dramatically increasing profit, no one in the recording industry is bothering.
There is no need for any of Mr. Craven's security encryption schemes disguised as sonic improvements.I agree (if it would be the only aim of the idea).
Play the ball - not the man.... and try not to kick balls in a glass house.
Actually I made several technical comments:
Of which my main point: I wonder why no real, total AD/DA loop measurements are shown anywhere.
The other being the measurement with "correct impulse responses", ie. measuring a DAC not only a not existing, abstract sequence of (one) sample.
Regarding your technical arguments elsewhere:Since when is latency a distortion...?It may be a limiting factor for practibility reasons, or a simple inconvenience. But in replay audio it is (AFAIK) of no concern at all.
(It is of concern in live electronics, PAs and filtering.)
I can understand that eg. a mastering engineer isn't too enthusiastic about an additional treatment of his files for (at the moment) dubious advantages or dubious advantages in the market place.
I asked MQA for MQA treatment of my recordings and got no answer. :-)
My main doubts when SACD and DVD-A came out, was that
a) the differences between DACs were IME considerably more audible than the difference between the SACD and CD layer on a good quality Sony player. (And I didn't prefer SACD on every aspect).
b) the user interface of DVD-A was f* up from the beginning.: A sad tale.
The copy right protection of DVD-A was also of Bob Stuart origin...
c) there were some simply amazing PCM recordings on DAD (Classic Recordings), ie. a non copy protected standard format. These sounded better (for me) than any DVD-A (or SACD) I have.
And - funny! - they were transferred from analog tapes.
I feel (...) that the stereo vs. multichannel, and SACD vs. DVD-A format insecurities helped to move audiophile audio into the back yard of consumer electronics interest.
MQA most probably wan't help either. I'm sorry about that.
And I agree that sonically optimizing CD-replay is much more relevant to 99.9% of the potential public and 99.9% of the recordings, ie. for the music.
And I agree that there are some mind-boggling high quality recordings in the CD-format. So it's the quality of the recording itself that matters most, ie. the microphones, electronics, rooms, setup and mastering.