Apple Logic Express 9 - Manual (Page 767)

Sonically, the result of using effects as effect processors sounds nothing like the result of
using send effects. Take the example of using a common effects combo, such as
Reverb-Chorus-Delay. Inserting the effects directly into the channel strip signal results in
a very different sound when compared to adding an effect send/return loop to the channel
strip signal.
Routing Audio in the Mixer via Insert Effects
You use insert effects when you want to add effects directly into the channel strip’s signal
flow. In this way, the channel strip’s entire signal is processed by the effect plug-in.
When multiple effect plug-ins are routed into a channel strip via inserts, they are said to
be routed in series. In this type of configuration, the output of one effect is added to the
incoming signal and becomes the input of the next effect in the chain.
The figure below illustrates this process:
On this channel strip, the
effect plug-ins
(Compressor, Chan EQ,
Tape Delay) are routed in
series.
Routing Audio in the Mixer via Send Effects
You use send effects when you want to isolate effect plug-ins from a channel strip’s signal
flow, or when you want to use the same effect on more than one channel strip.
767 Chapter 27 Mixing