The path below is where Logic expects to see your icons: ~/Library/Application Support/Logic/Images/Icons The "~" means your home directory. Remember the files must be 128 * 128 pixels in PNG format... Remember the icon file names must all begin with a number. If the number matches an already existing icons, it's substituted for your new icon. Logic's original icons are stored in: /Applications/Logic Pro.app/Contents/Resources/Images/Icons/ starting from "0.png" down to "324.png". Some icons aren't defined at all, so feel free to redefine your own. I don't have the complete list, but I know that, for instance, "12", "30", "46", "61", "76", "90", "105", "123" and so on, aren't defined yet.