I think it's Harosha's set up that uses a layer of foam on the wall behind the speakers. I'm thinking of using the same dampening material for my town house (share a commonwall with neighbor). Would it significantly reduce the boominess of my speakers? What should I use for my Harman Kardon subwoofer also?(from my computer's speakers) I'm just using a pair of Boston Acoustics shelf speakers connected to my Sony stereo system @ 20watts/chnl (really small/amateur stuff).