Using The Usb Input - Emotiva Differential Reference XDA-3 User Manual

XDA-3 DAC
Differential Reference

Using The USB Input

The USB Input on the XDA-3 is intended for connecting a computer or other computer-based
digital audio source. The USB input on the XDA-3 will be recognized by the computer or source
device as a standard USB Audio Class 2 external DAC or sound card, and supports PCM playback at
bit depths and sample rates up to 32/768k, without the need to install any additional drivers. The
XDA-3 will show up on your list of output devices as either Emotiva XDA-3 or SXW CTUAD768
(the high performance USB hardware in the XDA-3).
The XDA-3 also supports playback of DSD audio files via USB. The XDA-3 supports DoP-via-USB
at rates up to DoP256 and native-DSD at rates up to DSD512. Additional ASIO drivers, which we
provide, must be installed in order to support playback of DSD files on Microsoft Windows. Some
player programs for Apple computers reportedly include internal support for one or both of these
options as well.
Note: The USB input on the XDA-3 will work, without additional drivers, on both current
Windows and Apple computers, as well as many smart phones and other source devices, and
supports PCM at sample rates up to and including 32/768k. However, by default, both Windows
and Apple computers resample any digital audio they play to a preset default sample rate.
Many higher quality player programs offer ways to bypass this resampling but each has specific
settings and configuration options to do so.
Note: The XDA-3 supports true DSD playback via USB using two different methods:
"DoP" and "native DSD". Both of these methods are ways in which a DSD digital audio stream
can be encapsulated and sent to the DAC via a PCM audio stream over USB. Both deliver an
identical bit-perfect copy of the original DSD digital audio stream. (Native DSD uses packet
bandwidth somewhat more efficiently and so permits a slightly higher DSD sample rate to be
supported over a given connection.)
DoP, which is the more standard method, is supported by many high quality player programs.
In order to use DoP on Windows computers, you must install the ASIO drivers, which we
provide. Some Apple player programs also support DoP, with the necessary driver support
being provided internally by the computer.
Native DSD, which is really a variant of DoP, is more complex, and may require additional
settings or additional software. (For example, in FooBar2000, a separate proxy converter
program must be installed and configured in addition to the ASIO driver and support required
to support the standard DoP format.)
Note: By default both Microsoft Windows and Apple computers use PCM as their preferred
format for sending audio data to a DAC. In addition to this, some programs, when specifically
configured to do so, can send DSD directly to the DAC. However, when you play other types of
encoded or compressed audio files, like FLAC, or ALAC, or MP3, or AAC, the file is first decoded
by the player program, then sent to the DAC as PCM (or DSD). Therefore, you have no need to
worry about whether your DAC supports a specific file format, as long as your player program
supports it.
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