What is the difference between the 9.1 and 9SR . Basically the 9.1AV is 4 9.1 + a 9.1CS speaker. Besides the obvious technical differences between the 9.1 and 9SR, anyone know why the wharfedale brochure recommends using the SR for the surrounds rather than the 9.1s However the 9.1AV package is 4 9.1s?