So I have a newly constructed home and the surround sound was pre-wired. Each spot right now where the wire comes out there is just a wall plate mounting bracket. I have Sony speakers that are small and lightweight and I believe they use keyhole mounts. All but the center speaker have 1 keyhole. The center has 2 keyholes and there both on opposite ends of the speaker. So my question is how the hell I'm I going to mount these to the wall?