My room is in the basement. I have it sealed and insulated very well (sound insulation). I have also installed a solid core door. I have one vent leading into the room, and no return. The room is 19x12. When I have a few people in the room for more than an hour, it gets a little stuffy. The other side of my HT is the open area in the furnace room. I haev complete access to return ducts etc. What should I do to cool the room down? I am most concerned about room temperature and sound leakage. My house has two furnaces (one for up and one for main floor). If I add a return and link it to my ducting, will I not be creating a big whole for sound spillage upstairs? Could I just cut a hole in the wall and vent into the open basement? Would that transmit sound upstairs worse than hooking into the ductwork? Thanks.