There is a lot of talk about how to wire the DCX for unbalanced. Tie 3 to ground, leave 3 open, tie 3 to ground via 10K, 20K, 50K and others. I've tried them all.
What actually worked by far the best for me was a transformer on the XLR output. But of course that was the biggest, heaviest and must expensive option.

Your balanced resistor attenuator should work well. Let us know!