JONAS WITT With "deep sleep" I mean the state where your Mac is off. To learn how to use that feature, read http://metaquark.de/content/software/aurora/howto/index.html#preferences - basically, you'll need to enable auto-login for your user and have Aurora in your login items.
yummyDodd is right when he says that playback through iTunes is not 100% reliable (when you use AirTunes, for example), and that's why I included the fallback player in version 2.0 - this gives you all of iTunes' features (other alarm clocks don't support AirTunes, for example), but 100% reliability.
(Version 2.0)