My room is roughly 10ft wide x 15ft long x 9ft high. It is not rectangular because there is no door to the room. It sounds weird but look at the attached photo for reference. NOTE: I also live in a townhome and this is the finshed basement area. The basement is an english basement, it has drywall on the walls and ceiling. I am worried about that left wall that is next to neighbor. I dont want to tear down the wall and put rockwall/mineral wool/corning 703 etc. My two questions are, where and what should I start with for deading the sound on that left wall next to me niehgbors wall and also acoustic treatment. should I start with the window behind monitors? gobos? guitar center acoustic pack $100? DIY stuff?