Go to the settings page in wavelab and choose to record from the digital input of your card. For example, my prodif plus gives me options such as
Record from:
Windows something or other
Analog Input
Digital Input
ADAT 1-2 ... etc
ASIO
Aside from the ASIO, the others are all MME or WDM drivers. I forget which exactly. If I'm not mistaken with the Audigy (eew, sorry), you can even record whatever your card is outputting with the "what u hear" feature.
-Matt