The Epson may be an incredibly bright home projector, but it’s also, not surprisingly, louder than most. Claiming -39 db, at full power, is in line with the quieter commercial projectors in the 5,000+ brightness range (after all, that is its pedigree), but, 6-8 db noisier than the high side of most home projectors. Consider – Epson’s own 5040UB claims -31db.
The LS100’s -31 db in its quiet mode, therefore is also on the noisy side but acceptable in a typical room that it will be used in. Personally, the LS100 in low power was quieter than the 5040UB mode at full power, when viewed. That’s because quietness specs are from a set distance from the projector.
Remember, in the real world, you sit much closer to a table top or ceiling mounted normal throw projector than you will to an ultra short throw. In my theater, for example, it’s about 6 feet from my ears to my ceiling mounted projector, but 10 - 11 feet from my same seat to the LS100 under the screen. And, if I wall mount the LS100 above the screen, then it’s a good 13 feet away from my head.
Count the LS100 as reasonable, but not great, in terms of audible noise in your typical living room/family room setup. By the way, no issue at all with full power noise levels when I’m watching my sports. But full power and movies, I don't think work well together. That's OK, it's hard to imagine watching movies when you need full power's brightness.