I've been rescuing feral cats for 25 years and have had expensive audio equipment the whole time. Between 2005 and 2019 I had 10 - 14 living indoors full time in my house and still have 7 now. The floor standing speakers did become a target for a couple of them, despite having scratchers everywhere, so I wrapped them in mylar. I cut a sheet tall enough to exceed their reach and wide enough to cover the front and sides, then held them in place with ribbon as straps around the back held in place with velcro tabs. Very easy to remove when I want to use the speakers. Release the velcro from one end of the bottom strap, lift the mylar cover off and set it aside.
I also used mylar sheets held in place with velcro tabs to guard the AV stand from spraying, which I did have a little of elsewhere, but none on the AV stand. I can post pics if you're interested.
It has definitely required extra work, but it has actually worked really well in one of the more extreme indoor cat situations you're likely to find.

