Stereo amplifier units for background music and public address in a minimalist housing for installation into cavity walls and ceilings. Class-D amplifier design operates cleanly and efficiently with minimal heat dissipation, combined with an internal digital switch-mode power section, which enables easy connection directly from the local mains supply. Bluetooth compatibility enables wireless streaming of audio files from a smart phone or other enabled device in addition to 3.5mm Aux input and an optical digital audio input, ideal for integrating into A-V systems. For discreet and trouble-free installation without any need for table-top or cabinet installation, these amplifiers can be combined with many different speaker types to provide the ideal sound system for any small to medium space or deployed in numbers to create a wide area sound installation.