Hi. Here's the deal... a little while ago i bought a KLH 10" 125 watt powered subwoofer for my room. My room is 15ft x 20ft x `10ft, so it is somewhat small for a subwoofer. Well my parents get mad everytime I have my music on because the sub raddles the walls around me. My sister's room is right next to mine and there is this vent going from my room to her's, i have no idea why. Well when you're in her room you can hear the walls raddling and it sounds horrible. I was thinking about stuffing something in the vent so that the sound wont travel through it and I was wondering what the two holes on the back of the sub do because they are throwing out air which I think might be the reason its banging. Is there anything I can do to minimize the wall raddling from my sub without stuffing my walls with insulation? Also, just so you know, my subs have 4 spikes on the bottom that supposedly make your floor raddle less. My floors are carpet with wood underneath so i suppose they carry sound easily. I've read some of you guys using marble slabs underneath the sub and i saw one of those pad things for $60 but i dont know which ones work. Any advice would be great.