Metric Halo Mobile I/O - Manual (Page 331)

CoreAudio
331
Clock Sources
The CoreAudio specification provides the capability for hosts to control the hardware clock source. Some hosts
provide a user interface to do this, others do not. If the host does provide an interface to do this, you will be
able to select one of the Mobile I/O external clock sources directly from the host. If the host does not provide
an interface, you will need to use the MIO Console to select the external clock source. If you have selected an
external clock source using either the host or the console, you will not be able to control the system sample rate
from the computer. MIO Console will automatically reflect the clock source and sample rate set by the host.