Is that a door near the Screen? If yes, I'd place it near my seating position, in a corner behind. Best way is to do a subwoofer crawl (youtube this or google), to find the ideal spot for yourself, but a nearfield placement should be good in your room.
Screen: 5x12 Wilson Art Laminate Designer White
Receiver: Denon 2112Ci
Fronts: DefTech 8020ST
Center: DefTech 8040HD
Side Surround: DefTech SR 8040 BPs
Rear Surround: DefTech PM 1000s
Subwoofers: 2x HSU VTF 15H's