If that's the problem, you might try masking it via timing.

We used to be called to service or replace systems where rack fans came on when the system was turned on. With the room silent, the client would hit a button and several fans would crank up, reminiscent of a WWII plane scrambling scene. Once we discovered ATMs systems with thermostats, those days were gone: the system started silently; by the time the fans kicked in due to heat, sound was usually playing; when the fans stayed on after the system was shut down, who cared? Nobody was paying attention to the system then.

So, to translate this for a projector system, if you can get something started up that will pump some sound into the room, THEN start the projector, you might be able to mask a good deal of the thing the client dislikes about the projector.

If he dislikes the sound at startup, don't think he'll forget it in the middle of a movie: his attention will have been caught by the sound at the very start and it will continue to annoy him.