I am currently in the process of buying a new house, the new house has a theater room where the former owners are leaving their speakers because they are in the wall. I was able to find out that they are the DynAudio Audience 72 Series and I had a few questions. First, these speakers are rated for 4 ohms I have been reading about 4 ohm v. 8 ohm speakers and have not found an explanation of what the advantage is of 4 ohm speakers however it appears that most of DynAudio's speakers are 4 ohm speakers. I currently have a Sony STR-DA3600ES receiver which at 4 ohms will output 100 Watts. Will this be enough to run these speakers efficently? Second, the previous owners used one of the tower speakers for the center speaker which I had never heard of is this a common practice or should I look at purchasing a specific center speaker which is similar to the Audience 72's which are used as the R and L speakers?