No good pictures to post, as I keep all the good vintage stuff in rooms with doors kept closed to keep the cats out. However, they do inspect - and often try and open - every package I receive and sometimes the outgoing as well. The big boy of the group is 15.5 lbs and he eats shipping cartons like a pitbull going through a pair of shoes.
All three of them also like to help with shipping on the weekends; as soon as I put some packing materials out, they are climbing into the open boxes, burrowing under piles of bubblewrap, biting anything that's crackly etc.
Our HT system is in a common room, and one of the two younger cats likes to lie behind the center channel speaker where it's relatively quiet and nice and warm, as it sits on the shelf just above the Sony ES AVR and below a rear projector LCD TV. The other one has decided that it's a good idea to climb onto my prototype a/d/s/ front surrounds from the fireplace mantle, and from there onto the top of the TV. He knows better though, and as soon as I even start to get up to remove him he jumps off immediately. I may have to use some 2-side tape to make sure he doesn't knock a speaker off the stands in the process, though.
John