How to prevent visitors from touching your system

Only trouble I have had is people thinking the premium-finish floorstander nearest the entry door is a bar table for their drinks. The solution was directing traffic quickly away from the audio equipment wall. Visitors tend to be intimidated or incurious about industrial-looking electronic components. Turntable interests some folks, but it sits nearly 6' high, out of their reach. Of course, no cats or toddlers allowed.

Unfortunately, this method would definitely negatively impact sound quality. However, a bank of 5-foot-high sandbags and an M60 machine gun would do the trick quite nicely.

On a more practical level, just tell people what you would tell you kids: "Don't touch anything!" You could add: "This stuff is very expensive. "You break; you pay!".

I’ve had two instances of “hi-fi invasion”.
 

In the first case, a visitor mindlessly set a bunch of heavy stuff on top of my turntable, deeply scratching the plexiglas dust cover.  
 

Another time, during a family get-together, I was away for a few hours to pick up some groceries.  When I returned, my 20-something nephew commented how great my tube stereo sounded.  He had taken it upon himself to turn everything on (and it was a complicated high value multi-component system) to play music for the crowd!  No damage, I suppose, but it left me feeling invaded.

With so more kindness i only can say thanks...

And wish more than only my best for you...

@mahgister So happy you are back. I appreciate you.  

Everyone I know does not touch, they may look and admire. I believe they respect the fact that it is not theirs, so no touchie touchie....