RTFM
Options > Monitoring > Audition Mix
Smart Input Monitors only when recording a track. When playing back, monitors only the clips on the track, not the input.
Always Input Monitors the input at all times during playback and recording. Any existing clips on the input track are not played.
Options > Monitoring > Audition Mix
Smart Input Monitors only when recording a track. When playing back, monitors only the clips on the track, not the input.
Always Input Monitors the input at all times during playback and recording. Any existing clips on the input track are not played.