To help you fully enjoy your music, Audirvana offers a universal service that supports all the formats you need so you can play your audio files without having to modify or downgrade them. There are two main families of digital audio formats: Pulse Code Modulation (PCM) and Direct Stream Digital (DSD).
The PCM protocol is by far the most widely used in computers. It is supported natively by computers and describes each sample in absolute value independently of the previous ones. It is the basis of the WAV format, or Apple’s AIFF, which includes metadata. Depending on the clock used to digitize a PCM file, it can have 44,100 or 48,000 samples per second (or multiples of these values: 88.2 kHz, 176.4kHz, 96kHz, 192kHz, etc.). Each value is quantified on a scale of ±32,767 (signed 16-bit binary code encoding). With 24bits, we have more values reproduce more subtly the dynamics nuances, but the speed and size of the files increase. The CD or Red Book format, for example, contains a 44.1kHz sampling rate with 16 bits in stereo, i.e. a bit rate of 1,411 kb per second (1,411k = 44100 x 16 x 2). Beyond that are the High Resolution (HiRes), or High Definition (HD) or Studio Master formats.
To manage large sampling rates, including the file sizes, and storage space they require, compression formats have been developed that allow the transmitter-side signal to be encoded and then decoded during playback, hence the expression CODEC (coding and cecoding contraction). Compression may be lossless ( FLAC, Apple Lossless–ALAC, WMA Lossless, WavPack, and APE formats). Or it may be lossy, with the deletion of minor audio data supposed masked by more dominant data , and with data rates often between 128 kbps and 320 kbps, i.e. between 10 and 4 times less data than the CD format (MP3, WMA, AAC, etc.).
Audirvana was the first application in its category to integrate MQA (Master Quality Authenticated), a more recent PCM format that reproduces studio-master audio quality in a file small enough to be streamed or downloaded. Using a DAC with the “MQA decoder” maximizes MQA quality. If your DAC is an “MQA renderer,” decoding is shared between application and DAC, guaranteeing the same optimal quality. Finally, even if your DAC is not MQA-compatible, it can still read the files, and you benefit from their high resolution, especially from a two-fold sampling.
DSD is a protocol developed by Sony and Philips. It is based on binary encoding of sound at a very high sampling rate that is 64 to 128 times that of the CD. It thus offers very good impulse response. The code can have only two values: +1 (if the signal goes up) or -1 (if the signal goes down). Thus the pulse durations determine the amplitude of the signal (Pulse Density Modulation).
If your computer and your DAC are compatible as well, then you can enjoy end-to-end DSD playback.
The ASIO driver on Windows supports natively the DSD format. On macOS and with Wasapi, native DSD playback can still be achieved to a compatible DSD DAC by selecting “DSD over PCM” protocol in the Audirvana audio settings, which passes a native DSD signal in what the OS believes to be PCM. Keep in mind however that it halves the DAC’s maximum usable sampling frequency.
Even if your DAC isn’t natively DSD compatible, Audirvana allows you to decode and read all your DSD files, as well as SACD disc ISO images.
Since the DSD format consists in a very high frequency binary digits encoding (0 or 1), its sample values can’t be multiplied or divided, unless converted down to PCM and then back to DSD. So native DSD doesn’t allow digital processing such as volume control or EQ.