I just noticed that when I stand in the hallway and the door into our movie/music room, covers the back wall + back half of the projector (which means that the front vents are fully visible), the whirring noise is less noticeable:
If I open the door fully, the sound intensifies. Of course, this spurred me to placing the pj on the sofa in the middle of the room like this instead, turning it on and see what I could hear now:
From here, the high pitch sound is now slightly less
noticeable when I stand at the screen wall, some 9 feet from the sofa, than the same sound was when the pj was 15 feet away on top of the cupboard. So, I listened very closely from various angles and figured, that the sound most likely originates from the left back side (this is where it is defiantly most audible on our unit) - is this where the power supply is located?
So, imo is seems to be an issue with the sound, originating in the left back of the pj and being directed mostly backwards, being reflected by the rear wall and into the room.
So, could we do something about this with some sound absorbent material on the rear wall just behind the pj? I'm not sure that the dealer would consider it a warranty issue if we take it in, but we do plan to check out their demo model again in the near future, for a point of reference.
If this somehow helps anyone experiencing what we do, great. It could
explain why some might not really notice it (or consider it an issue), if their pj is hanging from the ceiling with no nearby bare walls to reflect/enhance the sound.
again, thx for all the inputs from you people. Great to see film fans helping each other out like this.