Building Exchange Chamber

Hi im relatively new to this Forum. However i have gone to school for audio engineering and built a pretty nice Studio. I'm in the stages of adding air conditioning. I was expecting to pay roughly around $3000 for a decent Hvac system (someone told me thats what it would cost) but i now i have learned it's gonna be around $8000 for a good quiet central air system. So i'm looking in to other options. I came across Rods Exchange chamber concept, and i think i'm going to go with that idea. I have just a few questions tho. I'm going to be building the chamber 4foot wide 8 foot long and 10 feet tall. It will share walls with my crawl space, and my crawl space runs right underneath my control and iso room. i plan on running 12 inch flex duct supply with a Inductor 12 in. In-Line Duct Fan fan. I will also be buying a variable speed control which will allow me to run whatever speed i need I will also be using returns in the crawl space. 12 inch flux as well. I plan on running 3 supplys and 3 returns. 1 per room. Im working in a 3 room studio. Control room 14x25 Live room 20x20 Iso room 8x8 My Through the wall unit is 25000btu. My main question is. Do i need duct fans in both supply and return? Any additional help is most welcome!! i'm sorry i have no pics and no sketches