...The mixer has a L & R main output. The NX4 has A,B,C,D input and 4 channels out (ABCD). How do I connect the L & R out to the power amp input and have A, B, C, and D outputs with independent volumes on each?...
Look at the right side of page 5 of the manual that came with the NX4-6000.
Set both of the switches to "stereo." This will be the 4 input to 4 output configuration.
Set both switches to "full range."
Use 2 Y cables to "split" each L and R output from you mixer.
(Buy 2 of these: Hosa YXM-101.5 XLR3F to Dual XLR3M Y Cable, 1.5 Feet)
Plug the 2 split outputs from L into the A and B inputs, and the 2 R into the C and D inputs.
You will now have individual control of each of the amp channel volumes.
A and B knobs will individually control the L signal outputs. C and D will control the R.
-Dennis