Thinking of lining the inside side panels of my 48u rack with some sort of sound deadening material. Was going to go with rock wool or the cheap self adhesive foam bricks you can buy off amazon. Was thinking of doing the same thing to the ceiling above where my rack sits and the walls behind as well. Mainly trying to cut down on the echo and high frequency whines. Anyone have any advice or suggestions? Maybe talk me out of it, or some other solution?