The IA-204 Series is a family of two input pre-amplifier/mixer or amplifier/mixers designed for mounting into a 4-gang deep masonary box, such as the RACO 698, the BOWERS 4-MB, or equivalent. The two inputs are both switchable between balanced Lo-Z microphone level and compact size balanced line level, allowing for simultaneous connection of up to four input sources. Their in-wall chassis’ are made of rugged .063” aluminum coated with an off-white epoxy based paint, and their faceplates consist of a tough polycarbonate overlay. Each unit also features a easy operation removable locking door with either a keyed camlock (standard) or a thumblatch camlock (optional). The IA-204P is only a preamplifier/mixer that provides the front end and in-wall controls for conventional rack simple room combining mounted amplifiers. The IA-204R and IA-204S are both or zone switching 20 watt amplifiers. The IA-204R provides a DPDT switch for simple room combining when used with the RCM Series, while the IA-204S provides a speaker select switch that can be used to turn off speakers in different zones. Both the IA-204R and IA-204S can supply 24VDC of phantom power to the microphone inputs.