PreSonus has announced that due to a design change by Apple, compatibility with AudioBox VSL interfaces has been affected:
We have discovered that the Apple has made a fundamental design change in their latest release of computers including the iMac series 14,1 (late model 2013), Apple MacBook Air 6,2 (late model 2013) and MacBook Pro (11,1 â€“ 13″; 11,2 â€“ 15″; 11,3 â€“ 15″; released October 22, 2013) are incompatible with PreSonus AudioBox VSL-series.
AudioBox 22VSL and 44VSL can be used as class-compliant devices by not installing the VSL software, using the settings in your DAW to control your I/O, and using Audio MIDI Setup for advanced configurations.
The aforementioned MacBook Pro, iMac, and MacBook Air models will not work with the AudioBox 1818VSL in either mode with VSL software installed or in class-compliant mode with no VSL software installed due to a problem with Apple’s hardware design that we cannot address. We suggest using a different computer with the AudioBox 1818VSL. Apple has been notified of the incompatibility.
We have tested and qualified that all of our other products including software products such as Studio One and Capture along with hardware products, including AudioBox USB, StudioLive 2442, 1642, 1602, StudioLive 32AI, 24AI, 16AI, FireStudio Mobile, FireStudio Project, and FaderPort, all work with these computers as expected.
If you need to uninstall your AudioBox VSL drivers, see this article from PreSonus.