You may not have heard of DSD (Direct Stream Digital)? DSD is the encoding format for Super Audio CD (SACD) which Sony and Philips released in the early 2000s. It had some success, but was launched just as music downloads were taking off, and SACD was a locked physical format which didn’t support downloads.
In 2011 some engineers got together and defined the DSD over PCM (DoP) specification which packed DSD into standard PCM packets so that the computer could transmit DSD to a DAC. DAC manufacturers quickly supported it, and today (2016) many DACs support DSD. The built-in DAC in your computer most likely doesn’t support DSD so you would at least need to buy an external DAC (see the last section for a recommendation).
Native DSD
Over the last 6 months I’ve been purchasing DSD music primarily from Native DSD. Native DSD is a fantastic website/company. The demand for DSD music is still relatively small but the website is very functional and their support is second to none.
So what is DSD? Why is it different? What is this article about?
Firstly I need to explain the recording pipeline and how that affects the music file. The main steps shown in the following diagram are the analogue recording equipment, the digital recording equipment, the digital editing software, and the final destination format. Other aspects that affect the recording are the performers, instruments, and room acoustics, but I won’t cover those here.
All of these steps are critical to the quality of the DSD format, or any format for that matter. For example, the analogue to digital conversion could record at CD quality and then the final format could be vinyl (not a digital format!). This CD to vinyl process would be considered heresy by many audiophiles since vinyl is considered much higher quality than CD. Another example would be recording in DSD but the final format being CD. A great recording format, but no advantage at the other end as it is still just CD format.
Over the last 6 months I’ve purchased about 16 DSD albums and I thought I’d share some of my findings.
Record Labels
What we will find is that record labels tend to take the same approach with their albums. In the table below I list some DSD record labels and their approaches for the above steps:
In the following sections I will talk about some of the differences between the above approaches.
Pentatone (Native DSD64)
I want to start with Pentatone because it is one of my favourites. Pentatone started in 2001, not long after the launch of SACD, with a focus on multichannel recordings (hence their name). It’s worth pointing out that one of the main features of SACD at the time was multichannel support (CD is only stereo).
Pentatone obviously care a lot about the recording process because their recordings sound fantastic. However, at the moment they are only recording in DSD64. What is DSD64? DSD64 is the original format used in SACD. In recent years there is now Double DSD (DSD128) and Quad DSD (DSD256). Many believe that DSD64 sounds much better than CD, because it has a sample rate which is 64 times higher than CD’s 44.1kHz (44,100 times per second). DSD64 sample rate is 2.8MHz (2.8 million times per second). However because DSD is only 1 bit, whereas CDs are 16 bit, DSD actually is noiser in the highest frequencies. There are two camps, some that love DSD, and others that prefer PCM (the format used in CDs). This issue with DSD64 goes away if the sample rate is doubled (DSD128 is 5.6MHz), and some say DSD256 is better again (11.2MHz).
If DSD128 and DSD256 are better than DSD64, why aren’t all albums released in those newer formats? One reason is size. A DSD64 album is about 3GB. A DSD128 album is about 5GB. A DSD256 album is about 8GB. That’s a lot of data for a single album!
So I wanted to start with Pentatone which sounds fantastic at DSD64. Let’s look at the other labels to understand why.
2xHD (Analogue to DSD128)
2xHD have a sample album called the Audiophile Hi-res System Test. It is available in DSD128, however it has been converted from analogue tapes.
What are analogue tapes? Audiophiles generally consider digital to be inferior to analogue. The best analogue tapes generally sound much better than CD. These are not the small commercial tapes from the 1980s, but large expensive tapes used in recording studios. So it should sound great? Audiophile analogue into DSD128?
To my ear, compared to the Pentatone recordings, it sounds like there is a slight veil. Directly recorded DSD sounds like the picure is in front of you, the recording from analogue to DSD, to my ear, sounds like you are looking through a window at the picture. A very slight veil in the sound.
So my preference is for directly recorded DSD rather than taken from analogue master tapes. You can find out this kind of info in the “Tech specs” tab for each album on Native DSD.
Something else worth mentioning is that 2xHD use a different converter for DSD64 and DSD128. They use DCS for DSD64 and Ayre for DSD128. I wonder whether this may also affect the quality of the sound? DCS produce very high-end converters. Using a different converter for different sample rates doesn’t allow us to do direct comparisons, and I am suspicious whether I don’t like the Ayre converter as much.
Reference Recordings (DXD to DSD256)
Reference Recordings have an amazing recording of Beethoven’s Symphony No. 5 and No. 7. It was one of the first DSD albums I purchased. However since listening to some other albums, particularly Pentatone’s, I thought it lacked that clarity and immediacy of DSD. Only recently I looked at the tech specs and was surprised it was edited in DXD before being converted to DSD256.
What is DXD? DXD isn’t DSD at all, it is just a very high sample rate PCM. DXD has a sample rate of 352kHz (8 times higher than CD). The sample rate is so high that PCM starts to sound quite good in DXD, I have a few recordings in DXD. However, even DSD64 is 8 times higher sampling than DXD.
So why edit in DXD and lose the benefits of DSD? The simple answer is editing. For a while, people didn’t think you could edit DSD files. DSD is 1 bit which is completely different to the multibit PCM formats. All editing software is based around PCM. It turns out DSD files can be edited without converting to PCM, but only a few companies offer editing software that does this. One of those companies is a Swiss company called Merging with their Pyramix editing suite.
In the Tech Specs section of the Beethoven recording the engineer explains that the release of the DSD256 version converted from the DXD was because they thought it sounded better than DXD. That is a reasonable reason, but it is worth pointing out that the original recording is not a native DSD256, it has a sample rate 32 times lower.
DSD256 is possibly the best digital recording format in the world at the moment. But this is a perfect example that you can have a DSD256 file, but if the data was processed to an inferior format beforehand, you may have an inferior recording with no way of knowing it. i.e. Having a DSD256 file is not the most important thing, it is how it was recorded and edited that it is more important. Note that a DSD64 file has 8 times higher sample rate than DXD, and hence effectively than this DSD256 file.
Eudora (Native DSD256)
I have a couple of native DSD256 albums, but they are very simple, only consisting of one instrument. The piano in Enrique Bagaria plays Haydn sounds present, real, and clear. Beautiful album.
Exceptions
I should mention here that there is more to a good album than just the aspects I mentioned above. But they might be helpful for those seeking quality DSD recordings. The key is try to find something that is 1) Directly recorded to DSD, 2) Edited in DSD (look for Pyramix), 3) Output as DSD. Higher than DSD64 is preferable, but I would prefer DSD64 if the above 3 requirements are satisfied, than DSD128 or DSD256 if those requirements aren’t satisfied.
A note on Genres
You don’t like classical? Sorry there isn’t much in DSD for you. Why the classical focus? There are a few reasons. The first is that DSD is difficult to edit. Even though the Merging Pyramix software supports native editing it is primarily around simple editing such as fades and volume changes. It can’t support the complex editing of a pop album (yet). The second is that DSD is a format for very faithful reproduction of live music. A lot of popular music is not a pure live experience. Classical, Jazz, etc. are typically live. The third is that audiophiles do typically like classical because of the complexity of instrumentation, the dynamics, and timbre. It is much more difficult to reproduce a live orchestra than a rap song. Which could possibly explain why classical doesn’t have a such a strong following in recent decades (i.e. it only sounds good if reproduced at a very high quality). And I wonder whether quality formats such as DSD and playback hardware may create a new enthusiasm for classical. It is worth pointing out that many audiophiles don’t like classical, but there is probably a larger proportion of audiophiles that like classical than non-audiophiles.
Where to start?
If you don’t have any DSD hardware, I would recommend something like the Resonessence Herus. With a good set of headphones this should change your perspective of recorded music permanently. A quality hi-fi system can cost you thousands but a good set of headphones will be cheaper and may sound better. The Sennheiser HD650 will probably blow your mind and go well with the Herus. You will also need some software to play DSD files. Audirvana+ is excellent and you will be surprised how even your non-DSD files will sound better.
