Volume Control Settings

Using Sound Max Digital
ASUSP4P8x MB

Win Messenger 4.7

Uninstalled QoS Packet Scheduler
Uninstalled Client for Microsoft

Using Stereo Headphones plugged into back of computer

When I first started using Win Mess. everything worked fine. Now the person
on the other end says I'm breaking up a little. Only change is he installed
SP2. I can hear him fine. App. sharing works and everything else. Have
made the changes suggested in this news group. What's up?

Also, under advanced control for volume control there are two check boxes
for AC3 SPDIF and PCM SPDIF, they are both checked, what is this setting &
could they make a difference?

TIA,
RBW