When you're listening to music anywhere, perhaps in that sweet spot, try turning around so that one ear is facing the speakers and the other is turned away. You'll notice that the sound (volume) you hear doesn't change. If you have a chair that swivels, you can turn around any way you like, and the sound you perceive remains the same. If you walk to a far corner of the room, parallel to the speakers, and then walk back along the same line to the other corner, crossing over that sweet spot, you'll hear the same volume of sound. I reckon the brain adjusts. It's the brain that does the hearing, not the ears. Ears are just the instruments the brain uses.
Your thoughts, please
(I tried this out in a somewhat smaller room, 4.2 metres by 3.8 metres. The speakers were placed along the longer wall, with the backs of the cabinets about 10 centimetres away from that wall. The speaker cabinets were standing on small, round tables with glass tops, and there was nothing underneath the glass. I tried this quite a few times.)
Your thoughts, please
(I tried this out in a somewhat smaller room, 4.2 metres by 3.8 metres. The speakers were placed along the longer wall, with the backs of the cabinets about 10 centimetres away from that wall. The speaker cabinets were standing on small, round tables with glass tops, and there was nothing underneath the glass. I tried this quite a few times.)