Can't get 5.1 Surround with Blu Ray on PS3, Logitech z-5500

[equinox]

Hey everyone,

I've been doing some research but still have been unsuccessful and would appreciate any help. I currently have a ps3 hooked up to my samsung via HDMI. I have my z-5500s hooked up to my hdtv via optical cable.

The lcd display on the z-5500 does not show dolby digital or dts option, only pro logic II. I went into the ps3 audio option settings and changed the output to HDMI and manually selected the dts and dds 5.1 options. However, the z-5500 does not pick it up. If i change the output to optical, i can not hear any sound because the fiber optic cable isnt connected to the ps3. I tried selecting bitstream on the BD/DVD option as well and I am still getting the blu ray movies in prologic II.

Has anyone else solved this problem or do I need to buy an additional receiver that has HDMI and optical input and outputs?