I'm curious to know if any of you folks with dedicated HT rooms have installed pre or post construction soundproofing and if so what methods and or materials did you use.
I've researched the 'room in a room' type construction methods and materials such as Acustiblock but I'm not sure just exactly how I want to do my soundproofing...if I do any at all.

When we built our house we put insulation in the interior walls off the theater room. We have a viewing room which has a window with two panes of glass seperated by 1" dead air space. We also put weather striping around the whole perimeter of the door, including the bottom... we can barely hear the sound ouside of the theater room unless it is turned up really loud.

Just got through building a home theater room in the basement...insulated all interior walls there. It makes a HUGE difference.

The ceiling above the washer and dryer is not insulated, you can hear it loudly. You can just hear (more feel) a slight rumble from the home theater w/ the insulation.

Probably one of the most important questions is how much do you want to reduce the STC? If you want complete isolation you would likely have to build an additional wall within the wall. A double wall construction is used in theaters. The typical budget technique usually involves insulation in the walls (Roxul or a spray foam - the spray foam is expensive) and a double layer of 5/8" drywall. In my design I am trying to achieve a double wall with 5.5" Roxul insulation and bracing between the studs on the media room side.