Diffusors (at least 1D diffusors) will not deaden the sound in the room, but can clear up and stabilize imaging while leaving liveliness in. If you have dipoles, then diffusors behind the speakers is probably a good idea. Otherwise, they usually work best behind or to the sides (but should be at least 4 or 5 feet away from your listening seat).
If you don’t mind a little (actually very little) work, and are in the USA near some lumber or big box hardware stores, you might want to try my DIY 2D diffusor design (actually designed via computer simulations rather than math formula or cut’n’try). See: http://www.diyaudio.com/forums/everything-else/269366-making-easy-diy-depot-sound-diffuser-panels-st...
If you are in a metric country (and don’t mind a little more woodwork), take a look at Tim Perry’s "Lean Fusers" at: http://arqen.com/sound-diffusers/
If you don’t mind a little (actually very little) work, and are in the USA near some lumber or big box hardware stores, you might want to try my DIY 2D diffusor design (actually designed via computer simulations rather than math formula or cut’n’try). See: http://www.diyaudio.com/forums/everything-else/269366-making-easy-diy-depot-sound-diffuser-panels-st...
If you are in a metric country (and don’t mind a little more woodwork), take a look at Tim Perry’s "Lean Fusers" at: http://arqen.com/sound-diffusers/