"sudo /Applications/Install\ OS\ X\ Mavericks.app/Contents/Resources/createinstallmedia –volume /Volumes/Untitled –applicationpath /Applications/Install\ OS\ X\ Mavericks.app –nointeraction"
So you’ve bought iTunes Match, which gives you access to shiny new 256kbps AAC versions of your audio files. But by default your iTunes library is still packed with your old files. So how best to upgrade all of those old files, in place, to the new versions?
Here’s how to do it—keeping in mind that you can only do this after you’ve completely turned iTunes Match on: