My experiences over the years has largely been along the lines of what "Cappucino" states in his response above here.
I must qualify my personal experiences, however, by saying that I have relatively limited experience thus far with the various processing and connection options, using the latest HD DD+ and DTS Master digital enccdings, but rather with older DD/DTS and pcm digital formats.
None-the-less, who wouldn't agree that, it sure would be great if we could all save a bunch of money by forgoing an AV preamp/receiver in our systems?! I mean, who wouldn't want that? I for one just have not found that as an option to yield supperior movie sound quality, at the very least.