Bravia and Klipsch

Hello,

I have a Sony Bravia TV and this is what I want to do. I want to play my audio through a pc based audio system, Klipsch ProMedia 2.1 iPod/Computer Speaker. My TV has a audio jack where I can plug the only audio cord from the speaker system. When I do this I change the speaker system in the TV config to external speakers. This do not work. I know this is a computer system, but I want to use this when I play a movie on my ps3 because the sound is so much better. Thank you for the help.