Just thought I'll write about my very interesting and somewhat disturbing experiences in the last one month listening to music through a few CD players. This post is not about building anything, and there's no DIY here, though I'm a DIYer. Hope this is the right forum for this. The "Lounge" forum seems to be for non-audio stuff.
Background
I've been learning to design speakers since 2002 or so, and I've built a few. I'm an engr by qualification, and I tend to believe in systematic design and measurement. I do not believe that power strips or power conditioners impact the sound of (well designed) modern audio gear, for instance, and I don't believe that CD transports do either. (I could be wrong, but I'm explaining my starting point.) I like ASR. And in terms of sound signature preference, I like clean, accurate uncoloured sound, with full detail retrieval. I don't like "rounded" sound, or "inoffensive, pleasant" sound -- it puts me to sleep. I would probably like the sound of any good studio monitors. I love the sound of my friend's PMC 3-way passive monitors with 12" Volt woofers, 3" dome mid, driven by his Luxman amp stack.
Now starts the story of the last month.
What happened
I used to believe that a DAC is a "solved problem" -- any two DACs which have flat frequency response and inaudible levels of SINAD across their frequency spectrum will be indistinguishable from each other. By SINAD, I don't mean a single number at 1KHz -- I mean the entire harmonic distortion profile across the spectrum, and I include 32-tone IMD in the measurements. But I have now had some listening experiences which have made me question this.
For the first time in my life, I had the following things set up in my bedroom:
I first bought one CD player. (Let's call it Player A.) I found it to be super-clean in sound, but I noticed that my brain was reacting to it by losing concentration -- I'd start one track, listen for a minute, and my mind would stray. And in objective terms, there seemed to be an etched quality, an edge, to the sound. I did not think much about it, and attributed it to the CD's mixing/mastering, and/or the earphones.
Then, due to a strange mix of circumstances (I was buying for my friend) I bought a second CD player (Player B), thinking I'll sell one anyway. I've never had the funds or the reason to do this before, in my life. And when I heard both in quick succession, the sound difference was quite remarkable. With the second player, gone was the edge, though I could hear full details. In fact, I could hear more detail now. And gone was my tendency to lose concentration. I was using exactly the same cables, headphone amp, and earphones.
I know that comparisons need level matching. So I went one step beyond level matching -- I tried to actively change the gain up and down while listening to one player, while keeping the gain unchanged when listening to the other player. The subjective impressions remained unchanged -- Player B sounded better, even when I made Player A sound louder, or softer.
I called my 18-year-old to listen. He's not interested in audio gear, but loves music, plays the piano, and has ears 42 years younger than me. I told him I'm hearing differences, and asked him to try the two players out. He used the HD650 (he diesn't like in-ears) and he played a CD he loves, which I had not used for my listening. It was "Retrospectacle" by Supertramp. He listened to just 1-2 tracks and said he can hear a difference. His exact words were "The second one is softer, but I like it more." I had not told him which was worse or better to my ears, but his identification of the "second one" matched mine.
Then I switched from the Atom Amp 2 to the RME ADI2 FS Pro, which, as you know is a complex piece of gear, and does A2D and then D2A before driving the headphones. I was not sure it would be accurate enough to let the differences come through, but it did. I could hear the same difference through it too.
To make things clear: I am not able to hear differences due to (a) changes in the RCA cables, (b) changes in the digital filter in one of the CD players -- it has two. (The other CD player does not give any choice of filters.) So, there are many things which are not impacting the sound in any way I can identify.
The subjective problem with Player A is not there if I listen to Hindustani Classical vocals. With that class of music, Players A and B sound different but both are enjoyable. But with Frank Sinatra, the subjective enjoyment is affected, partly because a lot of Sinatra (and Shirley Bassey, etc) are recorded with an edge to their voices, and partly because their orchestra arrangements have violins, etc which trigger that edge and make me shift to Player B.
Then a third little chapter was added to this -- I was lent a professional CD player (which is used for installations, 1U rack mount). Player C. The sound of this third player did not have any of the edge, any sharpness, of Player A. It was pleasant to listen to. But when compared side by side with Player B, it had less detail retrieval, and its sound had music notes which were kind-of one-note. For instance, the hard drumming in some of the Supertramp tracks sounded like "one note" from Player C and had layering and textural detail in Player B.
Why now? What changed?
I've been listening to CDs (and to FLAC ripped from CDs) for about 30 years. But I've never had two CD players at the same time in my bedroom, both of which are expensive enough for me to expect no audible differences. Plus, I've never listened to CD players (or any other digital source) other than USB DACs through revealing, high-resolution IEMs before, because these current amps were a very recent addition. It's possible I won't notice any differences if I use just speakers and the room modes start playing up.
My distress
This challenges my earlier beliefs. I used to believe that the DAC was a "solved" problem, and any two DACs which are made today without being forced to cut corners due to pricing pressure will have inaudible levels of noise and distortion, and will deliver a flat frequency response. I am ok being told that the professional-install CD player has less detail and realistic sound than Player B, but I am upset to admit that Player A sounds worse than Player C. And of course, I'm upset that two expensive CD players sound audibly different, and more important, one very clearly reduces the subjective enjoyment I feel, while the other makes me feel like losing myself to the music in CD after CD.
It's upsetting when old beliefs, based on which I've guided my audio journey for 20+ years, are challenged and I can't hide behind denial. I didn't do double-blind tests, but short of that, I did many cross-checks, and I can't deny that (a) there are audible differences, and (b) they affect the subjective enjoyment of music quite a lot.
Two reactions I expect
Some of you will be like my earlier self, and will say "You're deluded. Just do a double-blind test and your claims will fall flat. There is no audible difference between two such players, or the output of, say, the the Fosi Audio ZD3, which costs one-twentieth of some of your CD players." This is what I would have said, in less charitable language, two months ago.
Others will say "We have been saying that every bit of gear differs in sound from every other bit. We've been saying this for fifty years. The cables, the power socket, the audio rack on which you keep your stuff, the thickness of the metal used to make the enclosures, everything matters. You fools have been laughing at us -- now the shoe is on the other foot." Except that you'll say it in less charitable language.
I expect that these two templates will account for 99% reactions.
I am hoping that the remaining 1% will find value in my experience.
Further work
BTW, this story is not just about distressing discoveries. One pleasant discovery was the transparency of the ADI2 FS Pro, in spite of its AD-DA chain. Wow. What a device. Second: the impressive transparency and effortless driving power of the Atom Amp 2. Third: Player B has an awesome headphone amp, with three levels of gain and really lovely, transparent sound. I tried it out for just a few minutes, but one thing I'm sure of is that even with the middle gain setting, it has enough power to drive the HD650 to beyond acceptable levels, so power is not in short supply. IEMs sound excellent too, with any gain setting -- no noise detected.
Background
I've been learning to design speakers since 2002 or so, and I've built a few. I'm an engr by qualification, and I tend to believe in systematic design and measurement. I do not believe that power strips or power conditioners impact the sound of (well designed) modern audio gear, for instance, and I don't believe that CD transports do either. (I could be wrong, but I'm explaining my starting point.) I like ASR. And in terms of sound signature preference, I like clean, accurate uncoloured sound, with full detail retrieval. I don't like "rounded" sound, or "inoffensive, pleasant" sound -- it puts me to sleep. I would probably like the sound of any good studio monitors. I love the sound of my friend's PMC 3-way passive monitors with 12" Volt woofers, 3" dome mid, driven by his Luxman amp stack.
Now starts the story of the last month.
What happened
I used to believe that a DAC is a "solved problem" -- any two DACs which have flat frequency response and inaudible levels of SINAD across their frequency spectrum will be indistinguishable from each other. By SINAD, I don't mean a single number at 1KHz -- I mean the entire harmonic distortion profile across the spectrum, and I include 32-tone IMD in the measurements. But I have now had some listening experiences which have made me question this.
For the first time in my life, I had the following things set up in my bedroom:
- very good, transparent headphone amps (the JDS Labs Atom Amp 2, and the RME ADI2 FS Pro in preamp mode)
- a bunch of really transparent and uncoloured IEMs (Moondrop Chu II, Truthear Zero x Crinacle Red, Tanchjim One, Etymotic ER4PT), and a pair of headphones (Sennheiser HD650)
- two expensive CD players, in the $2,000-5,000 range
I first bought one CD player. (Let's call it Player A.) I found it to be super-clean in sound, but I noticed that my brain was reacting to it by losing concentration -- I'd start one track, listen for a minute, and my mind would stray. And in objective terms, there seemed to be an etched quality, an edge, to the sound. I did not think much about it, and attributed it to the CD's mixing/mastering, and/or the earphones.
Then, due to a strange mix of circumstances (I was buying for my friend) I bought a second CD player (Player B), thinking I'll sell one anyway. I've never had the funds or the reason to do this before, in my life. And when I heard both in quick succession, the sound difference was quite remarkable. With the second player, gone was the edge, though I could hear full details. In fact, I could hear more detail now. And gone was my tendency to lose concentration. I was using exactly the same cables, headphone amp, and earphones.
I know that comparisons need level matching. So I went one step beyond level matching -- I tried to actively change the gain up and down while listening to one player, while keeping the gain unchanged when listening to the other player. The subjective impressions remained unchanged -- Player B sounded better, even when I made Player A sound louder, or softer.
I called my 18-year-old to listen. He's not interested in audio gear, but loves music, plays the piano, and has ears 42 years younger than me. I told him I'm hearing differences, and asked him to try the two players out. He used the HD650 (he diesn't like in-ears) and he played a CD he loves, which I had not used for my listening. It was "Retrospectacle" by Supertramp. He listened to just 1-2 tracks and said he can hear a difference. His exact words were "The second one is softer, but I like it more." I had not told him which was worse or better to my ears, but his identification of the "second one" matched mine.
Then I switched from the Atom Amp 2 to the RME ADI2 FS Pro, which, as you know is a complex piece of gear, and does A2D and then D2A before driving the headphones. I was not sure it would be accurate enough to let the differences come through, but it did. I could hear the same difference through it too.
To make things clear: I am not able to hear differences due to (a) changes in the RCA cables, (b) changes in the digital filter in one of the CD players -- it has two. (The other CD player does not give any choice of filters.) So, there are many things which are not impacting the sound in any way I can identify.
The subjective problem with Player A is not there if I listen to Hindustani Classical vocals. With that class of music, Players A and B sound different but both are enjoyable. But with Frank Sinatra, the subjective enjoyment is affected, partly because a lot of Sinatra (and Shirley Bassey, etc) are recorded with an edge to their voices, and partly because their orchestra arrangements have violins, etc which trigger that edge and make me shift to Player B.
Then a third little chapter was added to this -- I was lent a professional CD player (which is used for installations, 1U rack mount). Player C. The sound of this third player did not have any of the edge, any sharpness, of Player A. It was pleasant to listen to. But when compared side by side with Player B, it had less detail retrieval, and its sound had music notes which were kind-of one-note. For instance, the hard drumming in some of the Supertramp tracks sounded like "one note" from Player C and had layering and textural detail in Player B.
Why now? What changed?
I've been listening to CDs (and to FLAC ripped from CDs) for about 30 years. But I've never had two CD players at the same time in my bedroom, both of which are expensive enough for me to expect no audible differences. Plus, I've never listened to CD players (or any other digital source) other than USB DACs through revealing, high-resolution IEMs before, because these current amps were a very recent addition. It's possible I won't notice any differences if I use just speakers and the room modes start playing up.
My distress
This challenges my earlier beliefs. I used to believe that the DAC was a "solved" problem, and any two DACs which are made today without being forced to cut corners due to pricing pressure will have inaudible levels of noise and distortion, and will deliver a flat frequency response. I am ok being told that the professional-install CD player has less detail and realistic sound than Player B, but I am upset to admit that Player A sounds worse than Player C. And of course, I'm upset that two expensive CD players sound audibly different, and more important, one very clearly reduces the subjective enjoyment I feel, while the other makes me feel like losing myself to the music in CD after CD.
It's upsetting when old beliefs, based on which I've guided my audio journey for 20+ years, are challenged and I can't hide behind denial. I didn't do double-blind tests, but short of that, I did many cross-checks, and I can't deny that (a) there are audible differences, and (b) they affect the subjective enjoyment of music quite a lot.
Two reactions I expect
Some of you will be like my earlier self, and will say "You're deluded. Just do a double-blind test and your claims will fall flat. There is no audible difference between two such players, or the output of, say, the the Fosi Audio ZD3, which costs one-twentieth of some of your CD players." This is what I would have said, in less charitable language, two months ago.
Others will say "We have been saying that every bit of gear differs in sound from every other bit. We've been saying this for fifty years. The cables, the power socket, the audio rack on which you keep your stuff, the thickness of the metal used to make the enclosures, everything matters. You fools have been laughing at us -- now the shoe is on the other foot." Except that you'll say it in less charitable language.
I expect that these two templates will account for 99% reactions.
I am hoping that the remaining 1% will find value in my experience.
Further work
- I will try measuring the performance parameters of the CD players using this test CD and my RME ADI2 FS Pro, for whatever that is worth. Better to have something rather than wait for someone with an AP5x5 to measure them one day.
- I have rips of all my CDs. And both these expensive CD players also accept digital audio in. So I'll feed these CD player SPDIF inputs from my RPi-Hifiberry-Digi-Pro with these FLAC files and listen to the music and see if I get these audible differences.
- I have one or two DACs: an Audiolab M-DAC and a Cambridge Audio 851D. I'll take the digital audio out from both these CD players and play them through these DACs, and connect my headphone amp to the DAC output to see if there are still audible differences.
- I will play some test tracks on both CD players (from CD-R I'll record from my FLAC files) and feed them to my ADI2 FS and record them to my PC at 24/96 FLAC, to share with you here (when I get the time -- don't hold your breath). I hope the Audacity software, which converts the audio to 32-bit float and then saves as FLAC, will not mangle the sound much.
BTW, this story is not just about distressing discoveries. One pleasant discovery was the transparency of the ADI2 FS Pro, in spite of its AD-DA chain. Wow. What a device. Second: the impressive transparency and effortless driving power of the Atom Amp 2. Third: Player B has an awesome headphone amp, with three levels of gain and really lovely, transparent sound. I tried it out for just a few minutes, but one thing I'm sure of is that even with the middle gain setting, it has enough power to drive the HD650 to beyond acceptable levels, so power is not in short supply. IEMs sound excellent too, with any gain setting -- no noise detected.
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I liked your post and I congratulate you for your ability to describe. 👍
However, I do not consider the FLAC suitable for Hi-Fi listening even if they are (defined as) lossless and I think that in any product sector any change implies as many differences that can be perceived more or less, but that cannot fail to exist.
If two things are not perfectly the same they cannot (and do not have to) provide equal results.
In my opinion there is no need to do DBT test because when it comes to humans it is about mistakes and when it comes to human senses even more.
But the above does not mean that you cannot perceive differences, it only means that if/when you share them on some audio forums you might find some detractors who unfairly mock you.
And I do not like people who mock other people hiding behind the word "Science" since even the measurements may not tell you the whole truth.
So, I like non-arrogant engineers and scientists.
Just because, in my view, Audio is not an exact science.
And also your narrated experience proves it.
However, I do not consider the FLAC suitable for Hi-Fi listening even if they are (defined as) lossless and I think that in any product sector any change implies as many differences that can be perceived more or less, but that cannot fail to exist.
If two things are not perfectly the same they cannot (and do not have to) provide equal results.
In my opinion there is no need to do DBT test because when it comes to humans it is about mistakes and when it comes to human senses even more.
But the above does not mean that you cannot perceive differences, it only means that if/when you share them on some audio forums you might find some detractors who unfairly mock you.
And I do not like people who mock other people hiding behind the word "Science" since even the measurements may not tell you the whole truth.
So, I like non-arrogant engineers and scientists.
Just because, in my view, Audio is not an exact science.
And also your narrated experience proves it.
Hi tcpip. thanks for sharing. Your test jogged my memory of an eerily similar thread many, many years ago, by another engineer:
https://www.avsforum.com/threads/establishing-differences-by-the-10-volume-method.1136745/
The methodology of raising/lowering volume seems near identical, the responses in the thread are very much as you predicted 😊.
It's very long and I will leave the conclusions to others, but it seems at least one other engineer has used your method before.
Well, that's how it been for a long time. "Solved" maybe is for the very but few last years - how old are these players?
Streaming might have a few advantages...
//
Streaming might have a few advantages...
//
@tcpip I saw your thread on ASR but decided to reply here as they firmly believe all DACs and CD players sound the same on ASR, and I wish to avoid that debate.
I have various CD players and DACs - and I too find they all sound different to varying degrees.
One DAC in particular (a vintage Arcam Black Box) can sometimes sound quite 'hard' with some male voices.
I have some CDs that sound amazing on some DACs but yet don't sound so good with others.
As for the comment above about not onsidering FLAC suitable for HiFi listening.... A flac file is a perfect replica of a wav file, so why wouldn't FLAC be any good for HiFi listening I ask?
I have various CD players and DACs - and I too find they all sound different to varying degrees.
One DAC in particular (a vintage Arcam Black Box) can sometimes sound quite 'hard' with some male voices.
I have some CDs that sound amazing on some DACs but yet don't sound so good with others.
As for the comment above about not onsidering FLAC suitable for HiFi listening.... A flac file is a perfect replica of a wav file, so why wouldn't FLAC be any good for HiFi listening I ask?
Ya I expect many members there will respond like I expected in my Type 1 template of responses -- "Do double blind tests, don't waste our time."
I don't get into those discussions. I have audiophile friends who (a) don't use a CD-R copy burned from an EAC FLAC rip, because stamped CDs sound better, (b) don't store ripped data in FLAC, only in WAV, because WAV sounds better. What I can't understand, I just avoid.
Simply because in my view it's like wanting to buy 1 dollar paying 50 cents for it.
However, it is just my preference. 🙂
Anyway, I can say that I've nothing against FLAC encoding and that I use that type of file in the car (bluetooth-ing my cell phone), but only because that way I can get related tags from file, otherwise I would use my beloved WAVs (PCM 44.1 kHz 16 bit) in my car too. 😉
You lose nothing by using flac, the decoded files are exactly the same as the input. Bluetooth, however, uses a lossy compression.
I wonder why you would use a compressed format that you then have to decode.
Could something happen during these two processes that we don't know about yet and that makes me perceive differences in sound that make me prefer WAVs?
Well, I just prefer WAV. 🙂
Furthermore, if file size was an issue a long time ago, nowadays it is no longer such just because there are mass storage devices that are so huge in very small sizes and prices.
So, for what reason would you do it? 🤔
If any, then in my car this is not a problem at all. 😉
Do either/both of the players give indication if interpolation gets activated (due to corrupt reading of the disc)? If there's dust/dirt on the pick up lens this might be an explanation.
The best way to compare them is with test gear and a test disc - sounds like something is badly wrong on one of them and that would show up with test tones.
The best way to compare them is with test gear and a test disc - sounds like something is badly wrong on one of them and that would show up with test tones.