When recording with the WireTap Pro controller set the file format in the Preferences. Click on the Preferences button, and open the Format pane. Set the file format in the File Format popup menu. Click on the Settings button to access the Sound Settings and set the Compressor, sample Rate, Size and Use: Stereo or Mono.
When recording with a Session set the file format in the Format pane of the WireTap Pro Recording Sessions window. Click on the Sessions button in the WireTap Pro controller. Create a New session, or Edit an existing one. Click on the Format tab to open the Format pane.