While SoundFont Pack and SoundFont 2 Sound Bank files carry different extension names -- SFPACK and SF2 respectively -- the two file types are closely related. If you're unfamiliar with SoundFonts, think of them as lossless audio samples. Files carrying the SFPACK extension are compressed versions of SF2 files. Convert or extract them to SF2 files with the SFPack program.
Download a free copy of SFPack. Double-click the zipped installation file to open it. Drag and drop the contents into an empty folder on your desktop.
Launch the extracted SFPack file. Click the Add File button, followed by the Files of Type menu box, and then select the SFPack Files (*.sfpack) option.
Locate the SFPack files, using the file explorer window's folder tree. Select the desired files, and then click Open.
Click the 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.
Click the Go button to begin extracting the SF2 files to the designated folder.
SFPack is no longer available from the original developer, Megota Software, but you can still download the program from various specialist audio websites, including the link in the Resources section of this article.