While .sfpack (SoundFont Pack) and .sf2 (SoundFont 2 Sound Bank) files carry different extension names, the two file types are closely related. If you're unfamiliar with SoundFonts, you can think of them as lossless audio samples. Files carrying the .sfpack extension are simply compressed versions of .sf2 files. If you need to convert, or extract, your .sfpack files to .sf2 files, you'll need the help of the format's namesake application, sfPack.
Download a free copy of sfPack. Double-click on the zipped sfPack file to open it. Drag and drop its contents into an empty folder on your desktop.
Launch the extracted "sfPack" file. Click on sfPack's "Add File" button. Click on the "Files of Type" menu box when the Add Files explorer window appears. Select the "sfPack Files (*.sfpack)" option from the menu box.
Locate your sfPack files, using the file explorer window's folder tree. Select the desired files, and then click "Open."
Click sfPack's "File" heading, and then select the "Choose Target Folder" option from the context menu that appears beneath the heading. Select an output folder for your extracted .sf2 files, using the File Explorer window that pops up.
Click on sfPack's "Go" button to begin extracting your .sf2 files into the designated folder.