In keeping with the goal of less too clean, we opted for a built-in speaker system from Stealth Acoustics. More then built-in, when done it is invisible. No grill. They get dry walled flush and then painted same as the wall.
Course that means they sit kinda deep in the wall. And with concrete walls, well . . . I guess that is what rotohammers are for.
Snow Creek Wall as seen from our property. And Snow Creek Wall as seen in the face of our Rumford fireplace.