I don't know about "echoes," but I have a "tinny" sound in certain spots in all 3 of the movies. One spot I know for sure is the beginning of GF III when Al Pacino is reading the letter from Michael to his children...sounds like he's in a tin can.

I've noticed this in other places in all 3 films. If I get a chance, I'll write down where it occurs when I watch the films and post it here.

I don't know if this occurs only with the DVD Trilogy or in all versions of the films.

-DJ