According to research by Harmon Kardon if you use two subs it is best to place them in the middle of two walls which are perpendicular to each other, rather than two corners. You will have to experiment.
Dual or single subwoofers?
I have a REL Britania 1. It's a great sub but too big to fit into my room where it would compliment my mains. I mostly listen to music (Loud Rock) I have been considering the Dynaudio Sub 500's (Pair) Mostly due to thier ability to fit in the corners of my room - I'm limited to 14" wide. Would I be better off to stay with the single REL or go with Dual Dyna's?