I am building an office system in a small 12x10 room. I have $1500 to spend on a pair of speakers. These will be placed close to the back wall 6-12 inches, and close to the corners of the room. So they will be close to all points of the wall, back, sides and corners. Is there a speaker that works BEST with this set up? And what are all the differences between the 4 speakers? Don't worry about sources or amplification, I will build around the speaker I pick.