DSP AQ Development
dsp_aq.rar (Source Code)
is a DSP FFT equalizer effect which I have written in C++ for WinAmp.
It uses wxWidgets for the GUI.
There are project files for Microsoft Visual C++ for DSP AQ.
But you'll need to create some filter for it to be of use.
Best is to measure the frequency response of your speaker system
using a good microphone and Audacity or some other nice Audio editing tool,
and then apply the aUCBLogo program generate_eq_preset2.lg to it.
Or you can use DRC, but that's too sophisticated for me. ;-)