Sound Field Plug-Ins : Down Mixer : Source

Source
The Source section of the Down Mixer plug-in provides controls that let you mute, invert the phase, and adjust the level of each input channel to the Down Mixer.
Mute
When enabled, the Mute button mutes the channel input to the Down Mixer.
Phase
When enabled, the Phase button inverts the phase of the channel input to the Down Mixer.
Level
You can adjust the level of the channel input to the Down Mixer from –45 dB to +12 dB. For stereo to mono down mixing, both the Left and Right channels are mixed to summed mono. For greater-than-stereo multichannel down mixing, the following rules apply:
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All left-channel sources (L, Lc, Ls, Lss, Lsr) feed to the left channel (L) of the down mixer.
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All right-channel sources (R, Rc, Rs, Rss, Rsr) feed to the right channel (R) of the down mixer.
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The center channel (C) and low-frequency channel (LFE) are panned center into the stereo field of the down mixer.
Meter
The level meters for source channels always show the input level (pre-fader) for the channel regardless of the Source Level setting.