Download new DRM-free audio tracks from the iTunes (or any other) music store and you’ll find that they are professionally produced, edited and do not need any further work. This is due to the tracks being sourced directly from the music publisher and not ripped from a CD.
However, we’d be that your music collection is more diverse than just tracks from an online music store. Most people have obtained live tracks from their favourite bands, mostly obtained by bootleg sources, or rare tracks they’ve obtained from other locations. You may have a number of tracks that you’ve sourced from LPs or cassette or simply can’t find some tracks (especially remixed tracks) that were only released on 12” vinyl in the 80s. If so, you’ll need to grab those from your vinyl and you’ll need a mastering program to make them sound half decent.
WavePad Sound Editor is a tool which you can use to process and master your audio tracks. You can cut out parts you don’t need, fade in/out the track and even add various effects to either the entire track or track segments.
If you’re a professional, the free version will be rather limited and there’s a Master Edition available with many additional options.