Texas Instruments' audio solutions giude. Quite worthwhile to scan ... clears up a lot of definations about the complicated world of digital and analog chips, usefulness for DIY purpose, etc ...
http://focus.ti.com/lit/ml/slyy013a/slyy013a.pdf
I especially like the diagram on page 3 ...
http://focus.ti.com/lit/ml/slyy013a/slyy013a.pdf
I especially like the diagram on page 3 ...