Q: I know that iTunes and other apps can play high-resolution audio files on the Mac, but my D/A converter doesn’t seem to be changing sample rates. What am I missing?
A: The Mac natively supports up to 96kHz playback sample rate with up to 24-bit resolution. To play a file back at high resolution from iTunes or other apps, you also have to set the system for higher-resolution operation. To do this, open Audio MIDI Setup. Select your desired output device. Change its sample rate to 96kHz. Now, 96k files will play at the proper rate. Files with lower rates will be upsampled to 96k. (This will not improve the sound quality of files recorded at lower sample rates.)