Thanks for the reply. But, I must say those links do not come close to supporting your earlier statement that player decoding always results in a 4dB reduction compared to AVR decoding. (Here's your claim: Your symptoms are consistent with having the player configured to decompress the audio tracks and send multichannel LPCM over HDMI to your AVR. That method seems to always result in about a 4db reduction in sound level when compared to decompressing the audio in the receiver.
That thread runs through the usual discussions of digital vs analog (not relevant here), dialnorm (which does not account for player vs. receiver decoding differences), and a host of other comments not related to volume.
That's the only part of the thread related to PCM vs. bitstream volume and that was a test done by one individual on one movie using PLIIx processing that compared the LPCM and TrueHD outputs from a PS3 Slim to an Integra processor. When you read through the subsequent discussion, led by Sanjay Durani, it's clear that this test doesn't establish much of anything one way or another. At best, it would be limited to what the PS3 does with PCM output, a machine specific finding.
As you know, I responded to that post in that thread shortly after you posted it. Dolby is saying some manufacturers attempt to compensate for dialnorm by adding their own adjustments on top of the dialnorm reductions done by the decoder. Dolby decoders will adjust for dialnorm exactly the same way regardless of whether the decoding is being done in the player or the receiver. But, then, some players and processors may makes additional adjustments of their own.
Bottom line: I do not think you have presented anything which supports the statement you made about player decoding being responsible for a 4dB reduction in volume compared to receiver decoding. Player vs. receiver decoding is a subject that generates a lot more heat than light and I think we should all make an effort to shed extra light here. Given the lack of substantiation, it appears your statement belongs on the heat side of the balance.