The HTZ310 is a Home Cinema set. Yes, it is basically a glorified DVD player, but it has all the bits you'd need to get 5.1 audio from your PS3 without breaking the bank and with minimal headaches in setting it up. Also, for those evenings where you just want to watch a DVD, then it saves having the noise of the PS3 whilst you are doing so.
That is to give you an idea how to wire it up.
Basically the audio from the PS3 runs to the TV over HDMI, which then passes it to the HTZ310 over the optical link. HDMI and Optical are both capable of carrying 5.1 encoded audio, so no problems there.