I've been using a philips home theater for surround sound in my setup for quite some time now. I connect all my devices to my Sony TV with HDMI, and then use the HDMI ARC port to connect back to the home theater. Everything plays very well over the system, even devices connected with SCART will play through the home theater system (stereo).
Yesterday I started up my PS3 again, which I haven't used in this setup yet. The XMB screen won't transmit any sound at all to the home theater system, and starting up a game will transmit very quiet, distant stereo sound to just the 2 front speakers. No subwoofer or center speaker action, let alone 5.1!
Turning off the system and letting it go through TV works just fine, all sounds play just fine. I've tried fiddling with the PS3 Audio Ouput settings, but I'm not sure what to pick there. Nothing seems to work, though. My PS4 is set to Bitstream (DTS), so I tried selecting a similar setting for the PS3 - to no avail.