Whether the mixing engineer maxes out the LFE or the main channel's bass is up for debate. Obviously this depends on the movie. Some movies have very loud and deep bass recorded in the main channels together with LFE and this seems to be a popular trend nowadays.
To make matters worse, some movies are recorded hot. But setting that aside, if you talk about the absolute maximum possible peak you would expect in a home theater environment, calibrating to 75 dB's per ch and using bass management (and assuming the disk was mastered at the correct levels), can we all agree that the max dynamic peaks attainable would be 120 dB's from the sub (handling all redirected content from the three main channels, in phase with the LFE ?) Because I'm talking about the maximum peak level possible.
Something that is not really discussed is the dialnorm situation. Dialnorm is not used in theaters. Movie theaters do not use bass management either.
In addition, if you have a THX receiver THX "Reference Level" calibration assumes that a Dialnorm value of -27 was used at the encoding stage of the DD DVD. If a DD DVD was encoded with a Dialnorm value of -31, playing back at THX "Reference Level" will add 4 dB to all of the Dolby Maximum numbers.
How is that for a kick in the preverbial pants ?
Have you guys watched M&C in both DD and DTS ? The soundtracks both net completely different levels. If calibrated to reference, the DTS soundtrack is
considerably louder than the DD one ! Which means considerably more output from the sub !
Which means that this 115 dB peak level spec is kind of meaningless.