The CD-RW900SX is a professional CD recorder and player that replaces the CD-RW900MKII. A slot-loading optical drive ensures years of reliable operation in the most demanding installations. This CD drive allows gapless recording when setting track marks, something not possible using off-the-shelf PC optical drives. A high-performance codec chip is used for A/D and D/A conversion for clean, clear sound quality with a frequency response of 20 Hz to 20 kHz ±0.8 dB. Various recording features like automatic track creation help the operator create polished recordings without constant supervision. The CD-RW900SX has unbalanced analogue input/output jacks as well as optical and coaxial digital audio connectors. Both the left and right analogue inputs have their own gain controls on the front panel. In addition, the digital input can be controlled for optimal recording levels from a digital source.