On the sound configuration page there's no way to specify precise numbers. If I grab the lowpass filter frequency slider, there is no way to restore it to its default value of 12000Hz, for instance.
Of course, I can edit the registry to get whatever setting I like, but there's probably a lot of users who wouldn't know to do that.
Also, you might want to provide an option to reset everything to default. It makes a good panic button in case somebody messes up their settings and doesn't know how to fix them.
