I have a pair of Kef R107/2 and a pair of Revel ultima salon both very highly regarded speakers in their day and an overlay of the measurements would probably show them to be within a db at any frequency, but I promise you they sound NOTHING alike.The SC4 is another great speaker that stood the test of time, but if you put it next to a new speaker in the price range the sc4 would sell for now, used you would hear the improvements.