You will also almost certainly need to go into the Windows Sound menu and select the mixer as the Default audio playback device and possibly set the level to max. There is a "tinkly" test signal. NB the mixer might show up as a weird name? "USB CODEC" or some similar ***t.
You will also need to setup recording but this time Level will almost certainly need to be set very low, from the default 100% to FIVE % or lower to reduce the crappy "16 bit usb whine" .
If you have any bother, come back and I can stickup some screen shots.
Dave.