Benchmark's Guide for Audio Playback using Mac
A Simple Guide to Configure Your Mac for Optimal Audio Quality
Set the correct sample-rate and set word-length to 24 bit
These are set in the ’Audio MIDI Setup' control interface, which is in the 'Utilities' folder:
(Applications -> Utilities -> Audio MIDI Setup).
In the drop-down menu titled "Properties for:", select the output device which you are using
Under "Audio Output", the "Format" should be set to the appropriate sample rate and '2ch - 24 bit’.
For iTunes versions earlier then 7, we recommend setting the sample rate to match the sample rate of the media (music) being played
For iTunes versions later then 7, we recommend setting the sample rate to the highest sample rate that your device is capable of
For iTunes versions later then 7, iTunes must be launched after the sample rate is set in AudioMIDI. Any sample rate changes made in AudioMIDI while iTunes is open will not change the sample rate of iTunes until iTunes is re-launched. Consequently, it will cause CoreAudio to sample-rate convert the audio coming from iTunes. The result of CoreAudio sample-rate conversion is significant distortion.
Set iTunes volume to "Full"
Volume settings below "full" may cause severe distortion, especially on version 6 and earlier.
The volume controls in iTunes versions 7.X and 8.X will not cause significant distortion. The user should not hesitate to use the volume control in iTunes v7.x and 8.X
This does not refer to the track-specific "Volume Adjustment" settings found in the "Get Info" menu. The "Volume Adjustment" setting should always be set to "None" for all tracks.
Read more about how digital volume controls affects audio
Bypass all audio DSP and plug-ins (EQ and any other audio 'enhancer')
For iTunes, disable 'Sound Enhancer' and 'Sound Check'
These settings can be found in iTunes by going to:
This article describes the process of creating an 'Aggregate Device' with the Audio MIDI Setup utility in Mac OS X computers.
Creating an aggregate device is a way to group multiple audio interfaces into one virtual device so that an audio application can speak to a single, solitary virtual audio interface.
Certain audio software cannot interface to multiple audio device drivers. In these cases, it is necessary to create an aggregate device if you wish to use multiple interfaces. For example, interfacing with Logic simultaneously via a device using optical and another device using USB requires an aggregate device to be created encompassing these two devices. This new group of devices appears as a single aggregate device to the audio application.