I'll use this model:
Since you didn't reveal what your existing system was I can't give a good answer.
The model I used has optical and a stereo mini-jack. I see no mention of a "COMPONENT IN/AV IN/AUDIO OUT" adapter.
Just setting up the above TV. How do I connect to my existing surround sound amplifier? On previous TV it was a simple phono connection to the L & R audio output channels. I've tried to connect using the "COMPONENT IN/AV IN/AUDIO OUT" adapter, but it doesn't seem to work. Which colours should be connected - there are 2 red, 1 white, 1 blue, 1 green, 1 black and 1 yellow.