Audio Recording : Selecting a Record Input Monitoring Mode : Selecting a Record Monitor Mode
 
Selecting a Record Monitor Mode
For record-enabled tracks to use Auto Input Monitoring:
*Select Track > Auto Input Monitoring.
For record-enabled tracks to use Input Only Monitoring:
*Select Track > Input Only Monitoring.
*To toggle between Auto Input and Input Only monitoring, press Option+K (Mac) or Alt+K (Windows).