Please forgive my ignorance, but I'm new to WDM. I've read through the DDK docs and think I have a grasp of the whole WDM audio streaming driver/minidriver concept, but a PDO-related detail escapes me: How/where is the PDO (Physical Device Object) created? If (as I'm guessing) it's done by the port class driver, then how does the port class driver come to know the association with the underlying audio hardware? All the documentation and examples seem to make this appear "automagical"! Can anyone shed light on this for me? Thank you! Jon