Tip: Shift + Option + Volume(up/down) adjusts volume by 1/4 of a bar.
Wow. I have been using OS X for quite a long time and this is the first i'm hearing of it! Thanks!
Holy crud! That's so hidden
Wow! How did you learn that?
They are producing a waveform that is constantly at the peak range of the digital-to-analog conversion. Most real-life audio recordings only very rarely, if ever, reach peak levels.
Some (older?) Hi-Fi equipment was in fact designed with this assumption and playing a constant sine wave at peak levels would very quickly burn something out.