I don't mind theme theaters, hell I've got one. What I can't figure is how you could possibly spend 3 mil on a home theater. Is the the entire room covered in gold?
You could use U boats are similiar at the interface of the stage and proscenium to seperate them and reduce vibration. I personally wouldn't worry about it all. I've found this makes virtually no difference whatsoever.
Tablesaw will make a much better and accurate cut. No need to make shallow or repeated cuts. Just set you blade hi enough to cut through the ply in one pass.