Do you use a tube preamp/amp? If so, the brand of tube can have an affect. In my system Sylvania is too sibilant. I sold the Sylvanias to a guy in town - his system is darker sounding than mine - and the Sylvanias were a great match. He said he was hearing details he had not heard before and loved it.
Also, in a friend's system good, high quality copper speaker cables sound great, but when we put silver cables in the system it was extremely sibilant. But like mine, his system is very transparent.
Also, in a friend's system good, high quality copper speaker cables sound great, but when we put silver cables in the system it was extremely sibilant. But like mine, his system is very transparent.