I've done extensive testing with DSP modes with my RXV-2500, and have come to the conclusion..... THX theater mode is clearly the most accurate, and the way movies are intended to be heard. Various DSP modes merely add distortion to boost SPL & add echo to different levels of severity.....
It's hard to distinguish exactly what's different between each DSP mode during a 'busy' movie scene, but if you single it out down to a single instrument, note, or voice......then toggle back & forth between modes..... woah, you really hear the difference in dramatic fashion, and it isnt pretty.
I just thought I'd toss that out there.....