I would recommend a parametric EQ that is of mastering caliber in the form of a software plugin. I find the dynamic linear-phase parametric equalizer that I am using works well. It is a *very* versatile tool, one that has no hardware equivalent, except maybe a very flexible combination of parametric EQ with a compander. There are ways to use this for your music on the PC. Either use a player that is VST plugin capable, or a program that will intercept audio before it goes out the digital output. I have both ways working on a Mac. I would think software that has the same functionality is available on the Windows PC.
I found an interesting suite of plugins. The company Voxengo makes my EQ plugin, and other tools that let you creatively sculpt the sound in various ways, some ways that have hardware equivalents, and some just plain creative. They make plugins for both the Mac and Windows PC. Otherwise, a hardware digital parametric EQ would work.
Edited by r010159 - 2/7/14 at 10:25pm