I've got a Panasonic SC-PT850 DVD HOME CINEMA Surround System, and whilst its excellent linked up to my Pansonic TV with viera Link, and it handles dobly digital and 5.1 via optical in really well... There is a problem....
The unit will not process DTS over optical in, meaning I've had to take that option out of my PS3 and the PS3 downscales the audio to 5.1 if DTS is being used for blu ray....
£399 I paid for the kit, and it lacks full HD support via Opitcal.... Of cause, optical is the only way for a PS3 to output digital if you do not have HDMI in via your surround system, so some home cinema systems can be very limited...
When I have funds I'll update to a proper home cinema amp with proper optical in as well as true HD HDMI in and out, this way I'll get the full HD sound from blu ray instead of it down mixing to 5.1..
Don't get me wrong, optical audio out of PS3 into optical in is way better then it going across your HDMI into your TV and then maybe pumping it back out via RCA to a stereo amp or built in TV speakers, as this is just stereo and will never be as good as digital out...
So, anything that handles optical in is better, but if you can see if you can get something in budget that handles DTS via optical as well...