Originally Posted by sworth
You can tell the difference if you are playing a true Dolby encoded program source. Movies separates (and perhaps boosts) the middle channel to make dialogue in Dolby stereo movies clearer. Music tends to mix the center channel vocals across the front sound stage, rather than channelling them just to the center. Basically, Movies treats the center channel as discrete, and Music treats it as a bridge across the normal phantom center in a stereo mix.
However, a lot of the differences aren't audible unless you have a source playing that is encoded in Dolby.
Ah, makes sense that it might be material dependent, so 2ch mixes that have a similar phase matrixes as a DPL encoding will have more DSU variation between modes than one that has less phase cross-mixing. I was using a fairly 'clean' modern recording for my tests before the post.
Since you just posted the Tomita info, I recalled one of my Tomita DPL CD rips (Snowflakes are Dancing) and sure enough, there is a difference now. It's subtle, but there. In movie mode, some of the rear channel activity is brighter than in music mode, and the center a bit more anchored as well.
I also went on and played a modern recording that is highly 'produced' (Sleepthief) and it responds similarly, as even in 2ch mode it has a very broad 'soundstage', so lots of phase cross-mixing in that mix. In movie mode, the vocals are more anchored to the center speaker, in music mode, it's a bit more diffused.
There is a distinct change in frequency balance switching between the modes on this recording, whether the mode has different EQ characteristics, or it's just that the routing of phased sounds is different in different frequency bands.