A limitation of Direct I/O is that it can only access the first interface in a system. Pro Tools uses Direct I/O for auditioning in the fades and import dialogs. Because of this, we constrain the list of paths that appears in the audition popup in the I/O Setup dialog to only those paths that reside completely on the first interface (i.e. all chiclets under the first interface). This way the selected audition path can be used as the audition path in all places (fades dialog, import dialog, or region bin).