Stereo Tool is a plugin for Winamp which adds several features to it. It adds advanced controls that allows to edit the sound in a professional way, as if it were the console of a radio.
It allows to separate the stereo channels, to modify the speed, to add filters (for example to correct errors in phases), to normalize the volume of a playlist, and several more options. It has a multi-band compressor (10 bands) which it does is divide the frequency spectrum into bands, and within each band apply a different compression. This makes it possible to adjust and normalize bass and treble in different subjects.
It allows to prepare the sound to transmit via FM. For that it has filters, stereo encoders, and RDS encoders.
Stereo Tool 6.32 is the latest version of this software, which was updated in August 2012. This version is free, but there is also a paid version with more features. Works with all editions of Windows, there is also a version for Linux.