The standard mixer has two sections: basic properties where you set up the desired levels for various inputs and outputs and advanced properties where you set up volumes of the speaker system components.
The THX Setup console is an independent application. This configuration tool is analogous to the Speaker settings window, but surpasses it in fine-tuning options. The console consists of two sections: Speaker Selection and Calibration. When in the first section, you choose the type of your speaker system, point at the central speaker (by defining its position relative to the monitor), test the attached equipment.
If you have some time to calibrate your audio environment, visit the Calibration section. You can set up precisely each speaker by entering its distance, level and angle with respect to the central one.