This utility is a real Swiss army knife with a lot of possibilities to work with multiple libraries in iTunes .
As you know iTunes allows you to work with multiple libraries , just hold down the “alt” key while launching the application to create a new library or select a different one from the default one. However, it doesn’t allow you to do operations between them, having to copy the songs or playlists manually and losing the associated metadata along the way (lyrics, covers, ratings, etc.). An alternative to this is PowerTunes, through which we can perform all these types of operations easily . We can even duplicate libraries or join them without fear of losing the associated data since they are saved in a common resource folder.
You also have two quite interesting options: to find entries in iTunes without an associated file (and which are displayed with an exclamation mark) using Spotlight and to do the opposite, i.e. to find sound files contained in the library which are not displayed in the iTunes lists.
Powertunes is priced at $20 per license , which I think is a bit expensive in my opinion but it’s certainly a tool to keep in mind if we have our music distributed on several Macs and ensure the integrity and metadata of all versions.