So after a lot of research around my theater area, I have found out that I can put an air return in the back of the theater pretty easily for the summer months, and for the upcoming winter, I bought a Panasonic FV-20NLF1 inline fan that will go into a special soffit behind my front screen wall and suck air from outside into the theater.
(Fresh air vent --> back draft damper --> insulated 6" flex duct --> FV-20NLF1 fan --> insulated flex duct --> duct boot --> theater)
I think that the fan is too big to fit into anything existing that I have, so I will build a front wall soffit and make it like my other sound proof soffits, but with an access/maintenance door. Then I will cut a hole for the duct to go up into the ceiling to get out to the fresh air, and then direct the other end after the fan into the existing soffits to get it on the other side of the screen wall (no need in making my false wall an air filter.
Which brings me to 2 questions.
1) Any economical ways to do a light filter of the air coming in? Just something to prevent tiny bugs or dust. I was thinking about making my own filters out of a layer of a nylon material (similar to cotton batting but not organic) and some sort of plastic mesh "cage" (like chicken wire, but plastic to eliminate rust) to keep it in shape and attaching it just before the fan sucks in the air into its "innards." It would be small and cheap. The outside air will come from the side of the house where there is about 60 feet to the next house and I live in Iowa where the air is always "fresh" :-), so I don't want to mess with carbon filters and such.
2) Does anyone know what type of fan speed switch works with these? I am anticipating that this is going to blast so much air that I will want to be able to dial it down, and inline fans seem to be finicky about speed controllers.
I know that I will need to power a vent to get the warm air to outside the house, but I wanted to get one FV-20NLF1 fan first to see how it fits, and what speed is required as I am not sure how much room I will have in the back of the theater to put a fan and if the 20NLF1 is more than powerful enough, then to suck air out, I might got with a 10NLF1 (max of 120CFM and 1.0 sones) at full speed since it is quieter at full speed already and its output is about 1/2 of the 20NFL1 (max of 240CFM and 1.4 sones)
I figure that worse case, even if I end up with more air coming "in" that if I really need to cool the space down, I can open the door a little to the theater, and let some of the excess air create positive air pressure in the house, although for an entire house, I doubt that it will be an issue at all.
So I am getting closer to my summer setup and winter setup getting started. Obviously I want to work on the winter one first, but the air return for summer is going into the same "hole" above the equipment rack as the fan exhaust setup for the winter, and I only want to tear that all down once.
For people wondering what the Panasonic FV-20NLF looks like, it is this: