I have VR4 GenIII's, which are covered in cloth & look like giant scratching posts. I was a bit concerned that the cat would tear them up, so when I hooked them up for the first time I cranked the system up to almost max volume & left them like that for 100 hrs.
It's been over two years & the cat has never touched them that I've noticed, although being a cat, probably scratched them once just to prove she could.