Thanks to all for the great information and recommendations. The air conditioning system for that side of the house does not pump much air into the theater. My HVAC contractor has proposed turning the existing vent into a return and running a new inflow duct through a larger vent in the ceiling. But he thinks that the room would still be warm because it faces the sun while the rest of the rooms supported by that air conditioning system are all in shade. So cooling the warmer room, the theater, would mean making the other rooms frigid because they are naturally cooler. He recommends the mini-split as the most efficient and the most quiet. And he would close off the duct to the theater at the source which would make the existing system operate with a little more efficiency. But I have no way of testing a mini split system or seeing it demonstrated before taking my chances and spending a lot of money. Either way, a fan in the equipment closet sounds like a good idea.
Air conditioning a home theater.
I have converted my den into a dedicated home theater and listening room. It is posted on Audiogon's Member Systems under Home Theater, Marc's Media Room Madness. The room is great but, since the warmer weather started, we discovered that our home's central air conditioning system is inadequate for cooling that room. Perhaps enclosing the previously open entrance to the room and the addition of carpeting and black out curtains is retaining heat more than before. There are various solutions. The two we are considering are to turn our central system into a zone system or install a "mini split" system. I would appreciate hearing from anyone who can weigh in on which system is more efficient and, most importantly, which one is quieter. Thanks.