Hmmmm...I see. I tried all kinds of rears for 7.1 and I can't hear them. I am very happy with 5.1 and side QS10s. I am also very satisfied with 2.1 with the v4.
Some songs do have more of a wow factor in 5.1. 2.1 sets the vast majority of the images in planes behind the speakers while 5.1 expands some images further to the sides. In some pieces, in 2.1, there are some wild effects where images come very far forward and sink back in as if the performer came closer to the audience and then retreated. With the M100s, some parts of Oxygene sound as if there are curved acoustic conduits between the tweeters and 5 feet forward and two feet up my sidewalls. Sound is sourced from the tweeters, goes into my sidewalls, comes out again and sinks back into the tweeters. In Radioactivity, puffs of highs come out of the tweeters and shoot 5 feet forward at the interface between my sidewalls and ceiling. I hear the puffs right at the interface.
The M5s don't make those effects but they have other benefits in that they acoustically disappear in my space. They are not as high fidelity as the M100s and they also have tiny 'nads to boot. The M100s plain out are more sensitive. The M3s acoustically disappear also but their fidelity is lower than the M5s. For some rooms and moods though, the M3s may be better than the M5s.
