Setting up USB Audio in Mac OS X
For bit-perfect playback in Mac OS X, we recommend media players designed specifically for audiophiles, such as Audirvana, Audirvana Plus, and Decibel
In general, regardless of the media player you are using, please be sure to:
- Set the software volume control to the maximum (0.0 dB).
- Turn off automatic gain adjustments, such as replay gain.
- Disable all DSP plugins.
- Ensure that CPU-intensive applications are not running since they may interrupt the streaming of audio data.
Bit Error Rate Measurement
Beyond the basic steps outlined above, each media player must be set up correctly and their bit transparency verified. Listening tests may give a hint of imperfections, but we simply cannot be sure until we measure the bit error rate.
We've selected Audirvana and Decibel and thoroughly tested them using a pseudo-random digital sequence that exercises a wide range of levels and frequencies. We've performed the tests for all combinations of standard sample rates (44.1K, 48K, 88.2K, 96K, 176.4K, 192KHz) and bits (16 and 24). An example of such a measurement is shown below, performed on 24-bit, 192KHz data (0 % error rate means that the bits are completely unaltered) :
Setting up Audirvana
Audirvana is designed from the ground up for audiophiles seeking the best sound quality. The following steps will ensure that the audio stream from your computer will be passed on unaltered to the DAC.
- Go to Preferences → Audio System, and select "Anedio USB Audio 2.0" as the output device. Click on "Exclusive access mode". "Integer mode" can be enabled, but it is not necessary since the conversion between a 24-bit integer and a 32/64-bit floating point number can be made back and forth without any loss of precision.
- Go to "Audio Filters" and make sure that "Forced Upsampling" is disabled.
Setting up Decibel
- Go to Preferences → General, and select "Anedio USB Audio 2.0" as the output device. Click on both "Obtain exclusive access" and "Adjust sample rate for best quality." The latter means that the sample rate will switch automatically to that of the source.
- Once again, ensure that all signal processing, such as replay gain, is turned off.
