I saw CE3K opening night at the best theater I've ever been in (except the Cinerama Dome), the late great Cinema 150 in Santa Clara, CA. Even with all the special installations they did soundwise before getting the movie, the saucers coming in overhead from the side still blew one of the theater speakers pretty badly (almost anticipating the glass shattering from the next reel, I guess!)
Dennis Muren shot the mothership stuff, having gone over to CE3K direct from STAR WARS' night shift crew. I'm pretty sure he's heavily quoted in the CINEFANTASTIQUE double issue on CE3K, which is probably where that info came from. Either that or maybe a Greg Jein interview in CINEFEX #2.