I would leave the grills in place.
I had a pair of Spendor floorstanders confined to my small listening room for fear
my kitty's would see them as yet another scratching opportunity. In order to move them into
the family space I decided to make an extra set of grills. Went to the local fabric store and bought
some nice black grill cloth and I was in business. The home made grills looked and worked great.
All my efforts were for nothing, because the cats never gave them a try.
I admit that it helps to have a computer driven table router to make this possible, but
they can be made with simple hand tools.
Good luck, and give the kitty's a little scratch under the ear for me.