i have been to DOLBY DIGITAL corporation's test room once.
it's just a small room for 6 people. the sound effect is better
than in a digital theatre. and their equipment is just the same
as those in many families except their decoder and room
decoration.

in fact if you go to a digital theatre, especially using DTS system,
you will have a great chance to meet 1 or 2 sound lag in a film.
because DTS sound track is always given in a cd-rom separate
from the original film copy. so as you know. a burned cd-rom can
not compatible to all cd-rom drive. so comes out the sound lag.