If they're open backed cab, don't turn them to the wall. Grill cloth is cheaper to replace than speaker cones.
I'm scratching my head really.
I read threads about how do I keep my kid/cat/dog from messing with my gear... I've never had a problem with it. A bit of training and discipline goes a long way.
We have 2 tom cats. They don't scratch anything. Too much like hard work.
Female cats on the other hand can destroy a sofa in one day.
I keep all my gear packed away when not in use.
I'd be careful with foam - some cats like to eat it, and then end up needing emergency surgery because of it.Make foam grilles for them from that eggcrate stuff. Foam is very unsatisfying as something to claw.
All too often, chasing a cat away from something you don't want them to scratch just makes them return with a vengeance.