If you want to be even more scared, check out the new Vivid Audio Moya 1 speakers that were announced this week. Those monoliths weigh almost 800lbs per speaker and are reminiscent of alien aircraft thrusters. 

https://twitteringmachines.com/vivid-audio-launches-their-new-flagship-speaker-the-moya-m1/

The diffusers behind my rack are indeed Vicoustic Multifusers. They do an excellent job of improving the clarity of the center image. I am a dealer for them and highly recommend them in that position and/or on the ceiling at first reflections.