Select the box from the main menu and choose create > compund > boolean.



Now under the command panel rollout pick boolean and press "pick operand B" button and click on the box 03 and you will see where the edges of the speaker covers will go. This way we will also make the holes on boxes.

Easiest way to do this is to make a cylindar in front view and set as shown.



Now select the box and again the boolean option, pick operand b and select the cylindar. When you are finished with drilling all the holes it should look something similar to the next picture.



And when you render it, looks something like this (shift + Q)