I'm thinking of having a mini cabinet installed in a wall that will have shelves and contain a stereo receiver, a Blu Ray player and maybe an Xbox. I'm thinking that a hole will be opened and then cabling will be run to the hold and a separate backing with shelves will be installed in the hole. I am also thinking of installing a powered subwoofer into a wall also. 1. Are there any possible issues I should be aware of before having this done? I will not be doing the work, though I want to think ahead about any thinks I should look into or be concerned with before doing this since I know nothing about drywall and electrical. Is this a bad idea for any reason? Thanks!