Apple Logic Pro 9 - Manual (Page 1180)

Working with the Surround Master
When you set the output of a channel strip to surround, a surround master channel strip
is automatically created in the Mixer. The surround master channel strip processes the
signals routed to the outputs, as configured in the Surround preferences (taking the
project’s surround format into account, of course).
You can insert surround effect plug-ins into the master channel strip.
Important: As soon as the master channel strip appears, the Insert slots of the individual
output channels are hidden, and any existing effects in the Insert slots (of output channel
strips) are no longer processed. Logic Pro remembers the Insert configuration, so when
you remove all surround outputs, the original output channel configuration is restored.
Bouncing Surround Audio Files
Bouncing a surround mix can create more audio files than your usual stereo bounce. Each
file is identified by a unique extension.
1180 Chapter 39 Working with Surround