Who'd a thunk it?   
I've had Apple's "Garage Band" software on my Mac for about 3 years and am just now figuring out all the things I can do with it. As Amos observed, you basically have to tinker around with it a lot because the tutorial is almost useless and even the "Help" notes aren't very specific.

But for several years I've been wanting a way to improve the sound (e.g., take out static or background noise or just do some EQ adjustment) in videos I've made of live performances (e.g., at Getaway), and I just realized yesterday that all you have to do is drag the video file into GB and then you can edit the sound, add tracks, etc.   You can do a little of this in iMovie itself, but to a much more limited degree.

I also know now that I could have been using GB all along instead of iMovie if I just wanted to record audio, not video. The menus didn't tell me how to do that, but all the controls are there (even if some are hidden in 'folded up' menus.

Anyway, I now realize some of the stuff I've paid studios to do by way of 'tweaking' a recording or even the recording itself I can do on my own Mac.

Now if I could just figure out how to remove or at least minimize distortion ("clipping") if it's on the original audio file!