I notice when I bistream I get the dialog normlization +4 readout on the AVR, with PCM that flag is not set leading to the overall lower volume. Once you volume adjust for it, all things are pretty much equal.
I was trying to bite my keyboard here, but anyway...
PCM does not have anything like dialnorm. Decoders in AVRs and processors are designed for a default dialnorm setting of -27 dBfs. The maximum setting for dialnorm, in other words, not using any attenuation with dialnorm, sets the audio level at -31 dBfs. When you see a reading on an AVR that indiactes "+4 dialnorm" or something like that, it means the dialnorm of that track has ben set at +4 over the default setting of -27. This means no attenuation is being applied by the decoder.
If dialnorm was the reason for hearing a difference in level between a Dolby/DTS bitstream and a raw PCM stream, the difference would be the Dolby/DTS track would play at a LOWER relative volume than the PCM. Not the other way around.
Back to the topic...there are a number of people who use only a basic theoretical knowledge of general digital technology to base their opinion that decoding Dolby/DTS in a player and sending PCM to an AVR is the same thing as sending the data in native bitstream form to be decoded in the AVR. These people have usually not done any sort of real world comparison themselves instead clinging to their own flawed reasoning and dismissing other people's real experience that there is an audible difference.
The simple fact is, modern AVRs process PCM and native bitstream differently. Different players use different decoders. There are different HDMI chips (transmitters and receivers) employed in these devices. In other words, there are far too many variables in this process to simply say, "bits are bits" and any difference one hears is either a simple volume difference, or worse, all in your mind.
I don't claim to be a scientist. This theory has not been tested under laboratory conditions. In the absence of hard science, we have only practical application and collected observation. While I do not claim to be an expert, I do have decades of critical listening experience with a huge variety of hardware and software. I've compared literally dozens of HD DVD and Blu-ray players and at least a half dozen AVRs. The main speakers in my system are reference grade studio monitors that are very revealing. I know what I hear. I don't need someone who hasn't even been in the room to tell me what is going on. When they have some hard science that proves their position over that of people who have actually listened to the differences, then we will have a substantive discussion. Until then, RobBas, don't let anyone tell you what you do or don't hear.