Engineered for superior sonic performance and system flexibility, the 640/641 offers the highest quality tools available. Even the input and output connectors were chosen for their standard use and reliability. ZonePRO products offer Euroblock connectors for balanced signals and RCA connectors to interface with consumer equipment often used in commercial applications; there is also a simple analog input bus that allows inputs to be sent from one unit to the next for unit and job scalability. The 640 and 641 provide all the necessary processing tools, from input processing such as gain control and EQ available on all inputs to highly sophisticated and dedicated features such as selectable paging microphone processing including triggering, de-essing, automatic gain control, compression and feedback suppression. . The heart of ZonePRO products is the routing module which provides, of course, primary source selection, but also source dimming for paging and priority override. The outputs also offer a wealth of processing designed for commercial applications, such as our patent-pending AutoWarmth® feature that was co-developed with JBL to provide natural low-frequency extension at any signal level. Each output also offers EQ, Bandpass and Crossover, Limiting and Delay filters for system optimization. With ZonePRO® all the tools are at your disposal to maximize the response of your system..PZA MORE SPECS