Thanks for all the comments and advice. Have decided that in fact cables are not the solution but that room treatment would be of great benefit. I'll have to work on that one.
Smooth and dark cables?
What lines could help dampen somewhat excessive sibilance in a system of very nice high end components that should be smoother in the upper mids. I have done all the room work that can be accomplished without serious spouse issues. As a very long audiophile I know philosophically cables shouldn't be used for tone controls but in this case it's my only choice. Have been thinking Transparent but would love some experienced suggestions.