I would tend to agree it is the "mastering" or "engineering" that is at the root of this. When I play SACD...I find that the multichannel sound is fairly equal across all speakers (only a slight variation at best). But, when playing a movie with DD or DTS...or playing a CD and letting the player "engineer" multi channel sound, I find a wide variance in sound levels.

With Blu-Ray, selecting UNCOMPRESSED PCM, and using analog out...I find the sound levels are very similar to SACD. Probably because they were mastered in multi channel as is SACD.

Marcus