I am also using Audio Osmosis...I am actually doing both. I am listening before reading and listening constantly after reading/studying, etc. Since the CD only gives you a brief overview and cannot stand alone, it helps me to hear the concepts and terms before delving into the actual reading and studying of the chapters.
But whatever way you do it, I think that listening constantly to Audio Osmosis when you are having some down time...i.e. driving, walking, exercise is key....