I am not familiar with the Denon but I was surprised to read your commentary? Though not as surprised as you were to write it I'm sure.
I found this one application note in a review:
"One of the most attractive feature sof this player is its ability to output HD audio codecs in their raw bitstream format. For someone like me who owns a dedicated AV processor, this is a preferred choice because the high quality components in the AV processor allow the sound to be reproduced exquisitely. To enable this feature HD Audio output should be set to Normal. If its set to HD Mix then the player sends the audio as a 5.1 PCM signal. HD Mix is actually a feature used for special pip content on a BD disc."
Would be worth checking these settings as the reviewer ran his into an Integra 9.8 and was very happy.
http://www.hometheaterhifi.com/dvd-players/439-a-secrets-dvd-blu-ray-player-benchmark-review.html
I personally do not like closed systems, so I would not invest in the Denon pre/pro... especially when it doesn't add any other capabilitiess
You can get the new Oppo BDP83 or one of the new Panasonics with both analog and HDMI, plus Ethernet, better DVD playback as a bonus and a much wider range of formats.
If I went this route I would start with the HDMI, postponing the investment in seven premium ICs, which ould easily exceed the cost of a new player.
If and when the analog test is deemed essential, or your curiousity gets the best of you, easy enough to add in the cables.
FWIW I have read nothing to support your theory - which is not to say that it is wrong, just that it is not commonly reported.
Could it be that your gear is not running to spec? Any posts about that from other disgruntled owners on http://www.avsforum.com/ ?