Headphone jack issue

My new to me system includes Rotel electronics, circa 1995. Preamp has a headphone jack but plugging in a headphone does not shut down the speakers, so the jack obviously does me little good.
Is this a preamp flaw or are there options such as a headphone amp, which I had never heard of until my wife started saying, "Sheesh, that's loud. Couldn't you use headphones or something???".
This stuff IS greek and/or rocket science to me, so I would appreciate suggestions made with the electronically challenged in mind. Thanks
Is there a selector switch that allows you to shut off the speakers?

Yes, there are headphones amps. More than you can imagine. A good site is:
No, no selector switch. It's a rotel rc 995

My question, i guess, is how to switch off the speakers when using headphone.

My memory from old receivers was that when you plugged in headphones, it automatically cut off the speakers. Would there be a point to a preamp that allows you to plug in headphones without shutting off speakers. I presume that using a headphone amp plugged into the tape output or some other auxiliary output doesn't shut off the speakers.

Sorry if I am asking this in an overly roundabout fashion.
Since it is a preamp, you could turn off the power amp.