PEAK Indicator
Detects the peak level of the post-EQ signal, and lights up red
when the level reaches 3 dB below the clipping level. For
XLR-equipped stereo input channels (9/10 and 11/12 on the
MG16/4; 5/6 and 7/8 on the MG12/4), detects both post-EQ
and post-mic-amp peak levels, and lights red if either of these
levels reaches 3 dB below the clipping level.