I want to start a small 250w stealth grow cabinet. This set up needs to be ultra silent and my 250W HPS light hums when it is on. Originally the ballast was in the light itself but I want to make it a remote ballast. With that said I want to build a sound proof/dampening box to place my noisy ballast. the ballast has to go next to my stealth cabinet and will be in my closet. What would be the best way to do make this box? Here is what I had in mind. I want to make a box who's sides are made of drywall I will then use a product called green glue ( its a rubbery caulk like substance that is placed in between pieces of drywall in order to significantly dampen the sound) in between a second layer of drywall to insulate the box and dampen the sound. Any other ideas on how I can silence my ballast?