Oh ok. The problem you have then is that the PS3 will not send the fully decoded signal through optical. It will send the uncoded signal that can then be decoded by your reciever but if you have an older reciever you are screwed as far as optical. You can use HDMI to carry it already decoded but if your reciever is that old it probably doesnt have HDMI switching. You may be able to run HDMI from PS3 to the TV then optical from TV to reciever. I dont know that it will work though. The bitstream should work, your reciever should decode it.... Hmmm. I dont know, you may have to use the cables that came with it to move your sound. Good luck man.
No, if your reciever is decoding the signal to 2 chan it should be able to decode it it DD I would think. Are you missing a setting on your reciever. Maybe it thinks it is recieving a decoded signal and is not trying to do it.