Adds 6 Balanced, Line Inputs to the 664
6 Full-Sized Fader Knobs
Sunlight-Viewable LED Metering
Arm Indication of L, R, X1 and X2 Buses
Big, Backlit Record and Stop Controls
PFL / Solo Toggle Switch per Input
Hi-Pass Filter per Input
Trim Level per Input
Output Routing to L, R, X1 and X2 Buses