All audio routing is done in the Audio panel or in the Audio Patch view mode.
In the Audio panel you can sum and split connections by holding down the ctrl/cmd key while selecting an input or output .
The Audio Patch view shows sources (everything that can produce audio) in the vertical column and target (all destinations) in the horizontal column.
You route audio by clicking (or dragging) in the grid.
You can also route audio using cues.