Under Audivrana Preferences and Audio System and Preferred Audio Device and Active Audio Device it should show your DAC and the range of sampling frequency your DAC is capable of.
On your Mac under Applications and Utilities open Audio Midi Setup your DAC should be selected. You should be able to use the drop down next to Format to select the maximum sampling rate your DAC is capable of.
On your Mac under Applications and Utilities open Audio Midi Setup your DAC should be selected. You should be able to use the drop down next to Format to select the maximum sampling rate your DAC is capable of.