Maybe I live a charmed life, but our cat has never showed any interest in our leather sectional or my MA 300-7Gs (the bottom of their grille is 18" off the floor). He does make regular use of his 3-Tier scratching post, maybe because it looks out over our garden and is far more interesting of a hangout than the speakers. We do occasionally rub catnip into the post, though. I would love to know the feline pharmacology of catnip.
