PCM v DSD Comparison: 16/44.1, 24/96, 24/192, 64x DSD, 128x DSD
There's a lot of buzz about DSD, talk of CD's demise, and music offered in various PCM formats from CD-quality up to 24/192. What's a person who cares about the quality of their music reproduction experience to do? And the answer is, listen. I got the idea to listen to various files in different resolutions and formats after receiving some comments on my Mytek Stereo192-DSD DAC review asking about double rate DSD or 128x DSD. Namely, is 128x DSD better than 64x DSD. It sure sounds better, mathematically! But the only way I know to figure out if one thing sounds better than some other thing is to listen. So that's what I set about doing.
Let's get a few things straight before we dive into listening. First off, this comparison is necessarily limited by a number of factors including the fact that I'm using one DAC, the Mytek Stereo192-DSD DAC (see my review here), 3 tracks each in 16/44.1, 24/96, 24/192, 64x DSD (2.8MHz) and 128x DSD (5.6MHz) all sourced from the same master tapes and all converted using the same process (see below). I do not intend to draw any sweeping conclusions since I'm aware of the limitations that the environment I'm listening in necessarily imposes. That said, I believe its fairly safe to extrapolate somewhat but I will try to keep my reaches within an arm's length.
Let me fill out the rest of my setup for this listening session: a PC running Foobar2000 connected to the Mytek Stereo192-DSD DAC with an Audioquest Carbon USB cable, a pair of Kimber Kable Select KS 1126 Balanced cables to the Pass INT-30A, and out to my DeVore Fidelity The Nines. I'm using a PC because at present the Mytek DAC only supports 128x DSD via ASIO.
Credit Where Credit Is More Than Due
I owe a huge thank you to Bruce Brown of Puget Sound Studios (you can read our Q&A here) for providing me with the music under scrutiny. Bruce was kind and generous enough to agree to create these files for the sole purpose of this listening experiment and I want to thank him for his time and for providing some great music to listen to over and over again.
Here's a word from Bruce on the process he used to generate the various file formats:
These were original master tapes that I had of these tracks. I made one tape dub of these 3 tracks that would facilitate the test more easily. The tapes were recorded to RMGI SM900 tape via a Studer A80RC MKII that has been greatly modified. This was also the playback machine. I created test tones so the tracks would have equal volume and the tape was played 5 times into each sample rate. I started off the test at 16/44.1 into the newer Korg MR2000sBLK using Mogami Gold 1 meter balanced interconnects. No EQ, Compression or Gain was used, just a straight transfer. The files were then transfered and labeled to an external hard drive and sent to you via zipped ftp.Thanks Bruce! I'd also like to thank Mytek for the very extended loan of their DAC for the purposes of this comparison.
And here's the details of the Foobar2000 setup for 128x DSD playback over USB (this is detailed in Mytek's setup PDF):
- Upgraded the Mytek to firmware to 1.7.1 (if you experience static along with your DSD music, make sure you've upgraded to this latest firmware and it'll go away)
- Install foo_out_asio and foo_input_sacd
- Go to File > Preferences > Output > ASIO and doubleclick foo_dsd_asio
- Select "Mytek Stereo192-DSD DAC ASIO" for ASIO Driver and "ASIO Native" for DSD Playback Method
- Open a Dale's Pale Ale (optional)
- Go to File > Preferences > Output and select foo_dsd_asio
- Go to Tools > SACD > Asio Driver Mode and select "DSD"
- Click "Apply" and "OK" and "OK"
There were three sample tracks provided [to avoid copyright issues the tracks names will remain private]. All PCM tracks were provided as WAV files and DSD as .DFF and again we have a 16/44.1, 24/96, 24/192, 64x DSD and a 128x DSD copy of each track. I loaded up all tracks into Foobar2000 and spent time listening. I listened to all tracks all the way through a number of times and then went back and focused on certain parts of tracks that emphasized or highlighted the differences I heard. And I will say up front that the differences between CD-quality and DSD make me want to put that word quality attached to CD in quotes.
Let's start on the positive side - music sounds punchy and bold and is clearly well recorded. There is also a sense of dynamic edginess, a hardness that creeps into the sound at dynamic peaks as if you're not hearing the full sound. This holds for each track and lends the music an overall sense of harshness as if it was recorded in too small a space. There's also an unnatural aspect to decay and reverb where they sound stunted reducing both a clear sense of the space of the recording as well as the full natural voice of an instrument or vocal or a finger snap. There's also an emphasis on transient attack that shifts the music's tonal center away from body.
Everything opens up as if there's more space in and around the recording. Decays sound more natural, musical images in space take on a more solid and fuller feel. Dynamics have a greater sense of ease, tone colors are richer and overall music sounds more natural and relaxed. On the loudest passages which are most prevalent on Sample #2, there is still some sense of hitting a wall as if some of the sound has been cut off.
The size of the recorded space is once again larger and much more natural sounding, even compared to the 24/96 versions. There's also a better sense of micro-detail or hearing exactly what the musicians are doing. A more intimate picture. This lends the music more drama, more impact because there's more variety to the sounds. Dynamics also appear to have a greater swing from soft to loud and there's an overall sense of ease that is not present in the previous versions. Upper frequencies take on a sweeter sound, cymbals sparkle, and horns sound more fleshed out and with less glare.
Holy crap! The musicians just relocated into real space. Finger snaps are 3D as compared to the PCM versions. Actually every aspect of the music is more dimensional. Dynamics are astoundingly natural-sounding and there's an overall ease to the presentation that translates into an almost uncanny sense of place. Instruments take on a more complex tonal palette and you can hear into the performance much more. Harmonica sounds like a harmonica as opposed to a piece of one. The CD-"quality" version sounds relatively dull and lifeless as if we're missing out on a ton of detail and subtle nuance.
Space is the place. Dynamic swing sounds unrestrained and fluid. There's absolutely no sense of harshness, edginess, or harmonic foreshortening. Music is rich and full. The scale of the recorded space is rock solid and stable and music emanates from this space in a completely natural way. CD-"quality" sounds like a cardboard cutout in comparison. There's a lot of "space" in the Sample #1 recording and the opening vocals resound in that space. With the double-rate DSD you can hear the size of this space whereas with the CD-"quality" version it sounds as if the singer's voice is hitting a wall. There's no depth, no complexity to this reverb tail with 16/44.1. With each step up the PCM bit/sample rate ladder and with DSD this tail gets more and more fleshed out, solidifying a sense of time (distance) and place.
The differences I noted between 16/44.1 and DSD are dramatic and easy to identify. Even though I was dealing with very good-sounding recordings, you could even say the CD-"quality" versions sounded good, when compared to higher rate PCM formats and DSD you get an increased sense of dynamic ease, harmonic complexity, micro detail, and a better sense of the recorded space (and time). A more natural-sounding presentation. The differences between the 24/96 versions and the 24/192 versions were not as significant but differences were there to be heard none-the-less. The same held for the two DSD versions so the most obvious jump was from 16/44.1 to 24/192 and DSD.
I admit that this could all be due to the Korg MR2000sBLK simply being better at converting to DSD and higher rate PCM as opposed to 16/44.1 or the Mytek DAC's ability to reproduce DSD over PCM. But I've also heard similar improvements with other recordings albeit under less controlled circumstances. My feeling is the differences noted between CD-"quality" and 24/192 and DSD are so marked as to suggest that the medium goes a long way in conveying the message.
Sample #2 opens with the band's percussionists playing soft to loud to louder still. In the CD-"quality" version this sounds flat and stunted as if it was recorded in a room just large enough to fit everyone, nothing has room enough to breath. When you listen to the same track in 24/192 or DSD you easily realize the musicians are mimicking the sound of a train approaching going from far to near, to nearer still as opposed to just going from soft to loud. And you realize this because you can hear into the recorded space and the music comes from a deeper, quieter place. This train reference is central to the message of this song, "...they curse this train that brought them to Johannesburg", so there's more drama, more emotional impact and the higher you go up the PCM ladder the more of this drama you get and you really jump right onto the tracks with DSD.
"How can I be sure..."
I think Bruce Brown was teasing by picking the song for Sample #1, each time I played it I wondered why some doubt was creeping in (kidding). I figured it was worth putting my findings to a test so I put all tracks on random play, turned off my monitor, took off my glasses (which is the same as being blind) and let the music play. Out of 8 random trials (this was all I had the patience for), I was incorrect once thinking that I was listening to was 24/96 when it was in fact 24/192 (this was my first trial and I rushed my decision). All other selections were correct.
But I'd say I got lucky with some picks. The differences between 24/96 and 24/192, for example, are not huge but there are differences if we listen closely. It also helps to listen to complete songs as opposed to switching back and forth between snippets. I do feel confident that I could identify the 16/44.1 version each time as well as identify PCM v DSD but even here Sample #2 and Sample #3 were easier to determine as compared to Sample #1. Then again, if you asked me to do this again in a few months using your computer's speakers all bets are off.
This was an interesting and informative comparison and I hope I conveyed a sense of the differences I heard. More importantly I'd like to stress how these differences can affect the way we perceive music and how they can impact the meaning of a song as opposed to just a focus on sound and sound effects. For me its clear that 24/96, 24/192 and DSD are superior to 16/44.1 in many meaningful ways and I've come to this conclusion based on listening to more than today's 3 tracks in different system settings. But the ability to listen to these various samples all generated from master tape using the same equipment and methods, thanks again to Bruce Brown, has helped to solidify this belief.
Where does this leave us? Well, there's the pesky issue of the quality of the original recording which obviously trumps all of the above. Then there are all of the variables, some of which we've touched on here, which makes drawing any firm conclusions potentially misleading. But to my mind when speaking in generalities why not go for ideals? Sure CD-"quality" can sound really good but higher bit/sample rate PCM and DSD can sound better. How much better will come down to the quality of the recording, the quality of the transfer, the playback chain, and your listening habits and preferences. Better still, if you value music first, all of this takes its rightful place in line.