ALC883 Multichannel Config help needed

[hogfan]

I have installed the Azalia package and the ALC883 driver package (choosing customize & 6 port) that I got from the sticky thread here. However, I am unable to get sound when changing from the default audio output in the AudioMidi configuration. I set up a new aggregate device and chose Quadrophonic ( I have 4.1 speakers). However, when clicking each speaker to test, I don't get sound. I am not even looking to get surround sound working, simpy sound from my front and rear channel speakers. Currently when I play music in iTunes (with default audio out), I only get sound from my front channel speakers. What else to I need to do to get the rear channels working? Thanks for any assistance. My Audio chipset is ALC883, and the MB is Gigabyte. Thanks for any tips.-hogfan