The first instinct for designers is to hide the speakers completely. Custom installers are called in to put the wiring and the boxes in the walls. Solid grills then cover the speakers and can be painted to match the interior. An audio lover I know once equated in wall speakers with hiring a quartet to play at a party, then putting them in a closet and closing the door. A slatted door, but still. Sound needs to travel. If it's only permitted to go through a small grill it won't sound as full and rich as it should. Much of it goes into the walls or gets trapped inside its own hidden box. In-wall speakers are a luxury to be sure, and a welcome solution to the design challenge of what to do with speakers. But they aren't the best solution for achieving high fidelity. To get that, we have to take the speakers out of the walls and put them into the room.