Audio Systems: remote volume control, master volume control, reostat

Question
how do you put a master volume control on a stereo that is in a common area,that lots of people  have access to the reciever amp. It's in a large common area in a Hostel.And people keep cranking it late at night.I would like a reostat or something like that.Like they have in bars....Thank you, Keith.

Answer
I need to see what the components are. Generally there are a number of things that can be done. One being inserting a limiter/compressor into the chain preventing the volume from exceeding a maximum gain setting and then locking it. Is this a distributed system? How many speakers? Is it low impedance or 70volt?