AudioSuite Processing : AudioSuite Window Footer : Preview Button
 
Preview Button
The Preview button in the AudioSuite window lets you audition the effect of a plug-in before you process the audio. By adjusting the plug-in controls while you listen to this audio preview, you can fine-tune the effect. Not all AudioSuite plug-ins support previewing.
Before you preview AudioSuite processing, be aware that:
The performance of the Preview function depends on the speed of your CPU. Faster computers preview AudioSuite effects better than slower computers.
Regardless of how many tracks and clips are currently selected, the Preview button will audition only the first selected stereo track or the first selected pair of mono tracks.
In Mono mode, only the first channel of any selected multichannel clip will be previewed.
If you are processing using Clip-by-Clip mode, the Preview function will preview only the first clip within a multi-clip selection. To hear all selected clips, temporarily select Create Continuous File from the File Mode menu before previewing.