How to prevent visitors from touching your system

My friends have their own hobbies. They for the most part understand that entering my listening room doesn't equal an invitation for them to touch everything. They might touch a speaker to feel the finish or pick up an album from my rack but they aren't turning knobs and pushing buttons. It goes both ways. I wouldn't go over their house and touch their stuff either. 

House of stereo.

They get it.

No touch.

When I got my first JBLs, Dorian S12 we had a cat. He liked the grills a bit too much. Being the 60s and in Chicago there were tons of plastic furniture cover makers. Had 2 flat bottom bags made of clear vinyl. Put over the speakers. Worked like a champ. Cat tried a few times but all he did was slide so he gave up.

Life is too short.  Let them touch, supervised, and clean it later. After the first time they handle it they will have their curiosity satisfied, especially if it’s little kids. 

As long as they don’t mess with the tonearm I really don’t care or see what harm they could do.  (I’m assuming they won’t be reaching around back and messing with cables😂).