One thing that might bear mentioning. The volume level on DVD audio is often very annoyingly low, open your mixer device, max out wave output and main volume, then max out the volume in your player and see if you hear anything then. If you have the volume levels set so your system sounds don't blast you off your chair, but crank your music only through the volume and amplification settings in winamp (different than the general levels) then that might be the problem.
regards,
Road Warrior