About to finish the dedicated HT room (well, not fully dedicated, will have a treadmill!) Having started the work in February, had no foresight and did not plan for air conditioning, figuring its in the basement and should stay cool in the summer and I can use a space heater in the winter (Atlanta area, so extreme cold is not a problem). But now, in the muggy days of early summer, I am realizing my folly and think I will need A/C, particularly when using the treadmill. One option is to branch off from the lower-level ac unit. The house has 3 levels but 2 units (none for the basement). For the existing finished rooms in the basement, done about 2 years ago, I branched off an 8" from the plenum and split it into two six-inchers. Now, however, I could not tak another six-incher as this would burden the main level too much. I think I am stuck, short of adding a whole new unit, but tell me if I could be wrong. So I got to thinking of a room a/c unit, but not a window-mount. Rather, one of those free-standing ones. I cannot easily see how it 'communicates' with the outside, though. Does one have to do something to the window (there is a window at the back), or what? And are they pretty quiet, ie, suitable for HT applications? Appreciate any feedback from those who have been there. Thanks.