Doc,
I have also heard that Sonar is not exactly the most cooperative program when it comes to sound drivers but I don't use it. I think the WDM drivers are the culprit, use ASIO instead.

My AC97 card doesn't seem to like other sound cards being around so it is deactivated in the BIOS.

I had managed to get the latency down to about 10-12ms in the SB Live for 48KHz/16 bits, using ASIO4ALL and then to about 8ms with the hacked KX drivers, if I remember well they are drivers made for Creative's own E-Mu line of cards that share the same processor as the Live and Audigy. Then I bought the Audiophile and the latency went down to maybe 5-6ms in 96KHz/24bits.

Also, the quality of the sound itself also changed, even not so good MP3's were playing with better clarity, they were sounding on the Audiophile like I got some new speakers. I could actually hear the difference.

Burkels,
please tell me more about your setup.