I plan to use the balanced subwoofer output of the 990 for the unbalanced input of a sub (intend on buying the LFM-1 along with the 990). The reason is because the route to the sub location involves going up a wall through the attic and down another wall (my house is on a slab, ugh!). This will be 50+ feet. I'll use an XLR to RCA transformer to go from balanced to unbalanced for the last few feet. Hopefully, this will allow me to benefit from the added noise cancelling properties of using the balanced output.

This is assuming that both the balanced and unbalanced outputs are active simultaneously.