DSD (Direct Stream Digital) is a high-resolution digital audio format commonly used in media like SACDs (Super Audio CDs). Since this format has a much higher sampling rate than PCM (Pulse Code Modulation), it allows for more detailed expression of the audio.
DoP (DSD over PCM) is a technology that enables DSD signals to be transmitted as PCM signals. Instead of directly playing the DSD file in its original format, it is encoded into a PCM format so that audio devices and transmission paths recognize it as PCM data. However, the actual audio data remains DSD. If the DAC (Digital-to-Analog Converter) supports DSD, it can re-convert the PCM data transmitted via DoP back into DSD, allowing the original high-quality sound to be played.
How DoP Works
DoP is essentially a method of encapsulating DSD data within a PCM transmission system. DSD data is wrapped in 16-bit or 24-bit PCM data and sent to the DAC, which recognizes and decodes it back into DSD.
Header and Data: DoP uses the upper bits of the PCM stream to carry DSD data, while the lower bits hold additional information to help the DAC recognize it as DSD.
DoP Transmission Method: Since DoP is transmitted as a PCM stream, DSD data can be sent via USB audio devices or other PCM-supported connection methods like S/PDIF.
Audio Quality: When DSD is transmitted via DoP, it is not converted into PCM, and the original DSD quality is preserved.
Advantages of DoP
Compatibility: DoP does not require separate transmission paths or hardware for DSD transmission, as it uses the existing PCM audio transmission system. This makes it more compatible with a broader range of equipment that can play DSD.
Simple Setup: Even if a device does not support native DSD, DoP allows the DSD sound quality to be maintained, making it easy to set up.
No Audio Quality Loss: Since DSD data transmitted via DoP is not converted into PCM but simply encapsulated in the PCM format, the original DSD audio quality is preserved.
DoP vs. Native DSD
DoP Method: DSD signals are "wrapped" in PCM for transmission, so they are processed as PCM data. However, there is no loss in sound quality, and only the transmission method differs for compatibility reasons.
Native DSD: This method transmits and plays DSD signals without any modification. It is used when a DAC can directly handle native DSD.
DACs That Support DoP
To use DoP effectively, an external DAC that supports DoP is required. Most modern DACs support DoP and can play DSD files using this method. However, for even higher quality DSD playback, a DAC that supports native DSD is ideal.
Conclusion
DoP is a technology that allows DSD format to be transmitted using PCM transmission methods, making it very useful for playing high-quality music on DSD-compatible devices. While native DSD may be preferable, DoP offers many benefits in terms of compatibility and convenience. Therefore, when sufficient DSD-compatible equipment is not available, the DoP method can be a useful alternative.
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