This article refers to the physical output connections on the rear of Zone units. It's vital to understand the difference between zones and outputs - several outputs can constitute a zone.
Click Line Output Source to select the signal source for the output you are working on. All zone sizes are processed in stereo. Mono/stereo reproduction is controlled by how you route to your outputs- either by using separate outputs for left and right or by routing just a mono sum. Note that any stereo zones require two physical outputs. Selecting the Line Output Source box will bring up this page:
Select the desired signal source for the output you are working with.
The process of source selection for an amp output on Zone 4P or 8P is exactly the same - just click Amp Output Source and select the source routing you require.