Lets put it this way: if you can put can lights in your ceiling space, then you surely can put a power brick in there. However, I really think you should have made your box slightly bigger and put the power brick in there.
Think about this though, Will the back of your box be viewable, or against a wall. If against the wall, strap the PS to the back of the juke using some metal strips and some screws. That will keep you from building a brand new box.