Apple Logic Pro 9 - Manual (Page 312)

2 Connect the output (or output pair) of your effects unit with an input (pair) on your audio
interface.
Note: These can be either analog or digital connections if your audio interface and effects
unit are equipped with either, or both.
3 Click an Insert slot of the channel strip you want to process with the external effects unit,
then choose Utility > I/O.
4 In the I/O plug-in window, choose both the Output and Input (shown as numbers) that
your effects unit is connected to.
5 Adjust the Input or Output volume as required.
6 Click the Latency Detection (Ping) button If you want to detect, and compensate for, any
delay between the selected output and input.
When you start playback, the signal of the audio channel strip is processed by the external
effects unit.
Some audio interfaces feature their own routing software, which you may need to use
to set up the chosen inputs and outputs for this type of use. Consult the documentation
provided by your audio interface manufacturer.
Most hardware effects units are MIDI-controlled. If this is the case with your effects unit,
you can connect its MIDI input and output cables to your MIDI interface. This allows you
to choose effects presets, and may also allow you to remotely control, record, and
automate the parameters of the effects unit from Logic Pro.
312 Chapter 10 Working with Instruments and Effects