I currently have just a standard 5.1 setup. I'am using 2 dipoles on both sides of me for my 2 surround channels. My question is if I wanted to add a back surround speaker making this a 6.1 setup should I buy a diople speaker like the 2 I have to the sides of me, or a direct radiating speaker with similar tonal qualities of the 2 dipoles. I just didn't know which way would make more sense.