How do I enable and control 4ch audio?

[Man_Without_Clue <love.chaser@gmail.com>]

Hi,

I was wondering how I can enable and control 4 ch audio for the audio 
device I got as below:

01:00.1 Audio device: Advanced Micro Devices [AMD] nee ATI RV610 HDMI 
Audio [Radeon HD 2350/2400 Series]

All i have is 2 ch left and right audio out, I don't even see control of 
the audio other than volume.

How can I utilize multi channel audio control?
Any interface?

A.K.