Okay, so how do you listen to the mix you are creating in the summing box? In the Control Room mixer, set the Control Room channel to Mix and then select the summing box as the monitor source on the left side of the mixer. (See Figure 16.14.)
Now you can listen to the output of the summing device as it will be recorded through the converters. Any coloration made by the summing device or the AD converters will be heard this way, allowing you to make mix decisions that are accurate to the final recording.