Once again, thanks for the comments. Here is my viewpoint:
The code does not say anything about the cords being accessible, let alone readily accessible. Nothing restricts the use of screws versus hinges. All it says is that the cord cannot be "concealed" by a wall. That tells me, for example, that if a cord were laid between the studs of a wall, but instead of sheetrock the studs were covered up with a transparent sheet of hard plastic that was screwed into the studs, this would not violate 400.8, because the cord is not ?concealed.? The issue is not our ability to get at the cord to fix it, nor the ease of access to the cord. The issue is being able to discover degradation or damage; the issue is being able to ?see? the cord.
That is the basis for my opinion that having the speaker?s cord plugged into a receptacle outlet that is located behind a grill is code compliant. As long as the cord is not concealed, as long as it can be seen through the grill, it passes the 400.8(5) constraint, even if the grill is screwed into place.