The CDR420 features dual XLR mic inputs with 48V phantom power, a SPDIF digital I/O, a USB 2.0 I/O port, a built-in speaker, a built-in microphone, and a headphone output that provides both dedicated monitoring level control with 4 modes of monitoring options. The USB port allows for both drive maintenance, via Windows XP disk tools, and the downloading of system firmware upgrades, thereby prolonging the professional life of the unit.