My previous message was all garbled. The PS3 does not output any advanced codec as bitstream (even if you set the output as bitstream under BD/DVD settings).
So, Dolby TrueHD and SACD are sent out as PCM regardless of whether the setting is bitstream or LPCM.
However, normal codecs such as dolby digital, dts, dts-hd (core) are sent as raw bitstream (for outboard decoding) if you set the output to bistream and they are sent as LPCM if you set the output as LPCM.
Your receiver will either decode the dd or dts bitstream or the PCM. PCM still has to be converted to analog before being amplified. Your receiver needs to support multi channel pcm through HDMI for this. DTS and DD bitstreams can come through HDMI or even through coax/optical.