An alternative to a kernel hack might be a library that sits between the player and the standard C library and changes data going to the audio device. You can use the partially linked player binary to achieve this.

Very, very interesting. Could some sort of plug-in idea be build around that concept? If it is possible to use this idea to get into the IO path for audio and file operations (how about video also?) there are a ton of cool things that could be done with that.

-Mike