The in-wall mixer/amplifiers shall be capable of controlling and mixing up to 6 independent input signals plus 2 inputs with the use of an expanding kit. The mixer/amplifier shall deliver up to 60 W or 120 W of output power. TOA plug-in accessory modules shall utilize the latest in surface mount component technology and include microphone, line, and special function models. The in-wall mixer/amplifier shall have a built-in 1-octave graphic equalizer with 9 bands to tailor sound system frequency response to room acoustics, reducing feedback tendencies and improving intelligibility. A built-in compressor circuit shall be provided to protect output level from distortion as a result of excessive input and keep it constant. The compressor’s threshold level shall be able to be adjusted. The unit shall have output terminals to match 4 or 8 ohm speaker systems, and shall allow a speaker distribution system to be connected to the 25 or 70.7 V terminals. A user’s blank space shall be provided for additional functions chosen by the user. This space shall accept an expansion kit (optional) to add two inputs. A key-locked door shall be provided to assure protection against tampering. Optional flush mounting and surface mounting boxes shall be available.