Where to start in writing an app to modify the output of all sounds on OS X?

Question

I am interested in writing a small utility to modify all audio output on OS X. I essentially want to apply a certain effect to the sound systemwide and/or via individual applications (similar to how Prosoft Hear operates).

Where would I start digging in order to accomplish this? Is this done through CoreAudio or are there other more direct option?

Answer 1

Core Audio plugins can achieve all sorts of things, those are probably your best bet. I notice you used the kext tag - it's of course possible to do this in the kernel, but that seems overkill.