assign nothing as default open with application I usually have bunch of audio files (.mp3) with my music and some other non-audio files (.asd) in the same directory. To play some music quickly I just select all in Finder and hit CMD + o to open them in my default application (VLC). The .asd files will also get opened, but I don't ever want to open them. They are used by the Ableton Live application, but aren't meant to be opened with it.

Is it possible to assign "nothing" as a default application for .asd files? I'm thinking possibly using defaults or other some other command-line trick, if needed.
RCDefaultApp - freeware, installs as a Control Panel. Yes, it's a million years old, yes it still works to Mojave, but may not at Catalina.

Extensions tab [might take a few seconds to populate], find your .asd in the list &amp; set the default to &lt;disable&gt;

New kid on the block for when RC is no longer viable seems to be SwiftDefaultApps though it doesn't seem to be so simple for this task.