The Williams AV FM 557 PRO D is a turnkey FM+ assistive listening system, combining an FM+ transmitter with wideband FM receivers to deliver an ADA-compliant listening solution for auditoriums, houses of worship, classrooms, and theaters. Receivers use OLED displays for straightforward channel selection across 17 preset wideband FM frequencies (72.1-75.9 MHz) and are fully expandable for larger audiences. The Dante-equipped (D) version adds networked digital audio distribution over standard Ethernet, simplifying integration with existing AV systems. The PRO designation adds Wi-Fi streaming alongside FM, so listeners can alternatively pick up the program on their own smartphone. The package meets 2010 ADA guidelines for hearing assistance and typically ships complete with transmitter, receivers, earphones or neckloops, and an ADA signage plaque.
