AntiAlias VST is a high quality mastering effect for the purpose of removing aliasing from it's input. Aliasing is the presence of harmonics in a digital recording that are above the Nyquist frequency, and therefore cause unwanted noise. While your speakers or stereo may have a top notch oversampling digital filter, not every piece of playback hardware is the same. With this plugin you can filter out aliasing at the time of creation, rather than expecting PCs and stereos to clean it up later.