4-channel mono mixing amplifier, with 4 active 120 W outputs, for setting up a multi-zone PA system. A switch allows each of the 5 inputs to be assigned to one of the 4 outputs. Thus, it is possible to reproduce varying programmes in different areas. Another advantage is that an announcement in one area will not interrupt the programme in another area. With the optional zone-paging microphone PA-4000RC, the amplifier can be extended to a 4-channel PA system. In combination with the fireman's microphone PA-4000FMP with integrated voice memory, e.g.an alarm system can be set up in schools.