Each 3db increase doubles the low frequency content below my 50Hz crossover. 99.9% of the time I listen to music at 0db, flat as shown below (or just as often with the sub completely Off). I usually find myself listening to action movies, though, at +6db and occasionally +9db.

Since the Velodyne has such linear low frequency output, I can only conclude that I (like you) prefer more low frequency content in the audio mix than is normally provided on dvd ... and it does vary significantly from flik to flik.

2001 Audi S8
2007 Toyota FJ Cruiser