SACD or DSD: The Differences, and Which to Choose

SACD and DSD appear together so often that the two terms are routinely confused. The distinction is simple: SACD is a carrier, and DSD is an encoding.

DSD, or Direct Stream Digital, represents audio as a one-bit stream at a very high sample rate. Standard DSD, often called DSD64, runs at 2.8224 MHz, sixty-four times the CD sample rate. Its quantisation noise is shaped so that most of it lies above the audible band. Higher multiples, DSD128 and DSD256, push that noise further out.

SACD, the Super Audio CD, is the disc format Sony and Philips introduced in 1999 to carry DSD. Its high-resolution layer holds DSD64 in stereo and, on many discs, multichannel as well, often with lossless compression to make it fit. Many SACDs are hybrid discs with an ordinary CD layer that plays on any CD player. The high-resolution layer is protected against copying and can only be read by an SACD-capable player. Many players also limit or convert their digital output from that layer.

DSD files are the same encoding without the disc. They usually come as DSF or DFF files from download stores, at DSD64 or higher rates. A computer or streamer sends them to a DAC either natively or wrapped in PCM frames, a method known as DoP, so the DAC must support DSD for this to work. Some DACs convert DSD to PCM internally, and some convert PCM to DSD; the label on the file does not guarantee what happens inside the converter.

The format also tells you little about how a recording was made. Some releases were captured and edited in DSD throughout. Many others were recorded or mixed in high-resolution PCM and converted to DSD at the end. Both can sound excellent; the recording and mastering matter more than the acronym.

Which should you choose? If you already own SACDs and a good SACD player, the discs remain a convenient, self-contained way to hear DSD, and hybrid discs keep a CD layer for everything else. For new purchases, DSD files are more flexible: they fit a networked library, offer higher rates and need no special drive, provided your DAC supports them. Whatever you choose, compare at matched levels, and judge the recording rather than the format.

Which Demograf Audio piece fits

• Prometheus: native DSD up to DSD1024 over I2S (HDMI) and DSD512 over USB, PCM up to 32-bit / 768 kHz.
• Hyperion: DSD256 over USB (Amanero), with a solid-state or tube output stage.
• Ulanor: a fanless audio computer that plays up to DSD1024 as the source for a DAC.
• Reference Tube DAC: plays PCM only, with no DSD, for listeners who prefer NOS multibit conversion.