Thanks Vincent, I think you have confirmed my understanding of the two different processes concisely, in particular that the Asio/Wasapi route bypasses the Windows control which Stan was originally referring to as a constraint which he resolved.
Although the Win7 implementation is a big improvement over XP, it is an avoidable additional process assuming the DAC can itself handle 16/24bit and 44-192 via Asio/Wasapi on USB.