The Sound Devices CL-6 Input Expander for 664 Field Production Mixer adds 6 balanced, line-level inputs to the 664. The Input Expander connects to the top or bottom of the 664 (see Mounting the CL-6) and includes 6 full-sized fader controls, PFL control, and highpass control, and dedicated L and R routing buttons for Inputs 7-12. The large, backlit Record and Stop buttons provide convenient access to transport functions. Other features include large, daylight-viewable LED meters (with track arm indicators) for tracks L, R, X1, and X2.