I have an Airport hooked up to some very powerful active speakers which don't have their own volume control. This means that the iTunes volume rocker is all the volume adjustment I have available. The problem is that it only has about 10 'steps', which is just way too coarse. Ideally I would like to have something like 30 steps. That would give me 10-15 steps in the volume-region in which I am listening at most of the time. Does such an app, terminal command, or plugin exist?