How to start creating an equalizer for Windows/7/8/8.1?

Question

Audio

I have a few specific questions. The choice of axes is not accidental - I read until then that there is a big difference in the architecture of sound reproduction in new Windows, hence the decision. The first question is where to start creating an equalizer? The second question is, in what language is it better to write so that this equalizer supports any hardware? And finally, where can I get the sources of the system files responsible for the sound?