Importing an Audio File Metro offers a variety of methods of MIDI and digital audio recording, including linear, partial track, punch-in and step-entry modes. Metro’s arrangement features facilitate linear or nonlinear section-based arrangements. This section of the tutorial focuses on recording and editing a linear multitrack arrangement. Let’s start out by constructing some tracks around an existing drum loop sample that was saved in AIFF format. To import an audio file: Choose Import Audio File from under the File menu. Locate the folder called Drum Sounds folder and open the file named Drum Loop 120.AIFF. Click the Convert button to import the file into the active Section. The next step in your first session is Looping a Track.