Linking to aac audio files is returning a 404

"I suspect this may be a problem with your web server configuration.
If the files are on the server, you shouldn't get a 404 response but it's possible that the server is configured to not serve .aac files and to return an (erroneous) 404 page (or that something similar is happening on a proxy between you and the server).
You could try changing the file extension to .m4a and see if you have better luck - the file should still open in your music player if it does download."