I read the "Wye" Not Rane note on summing boxes. The diagram above is taken directly from their discussion of a stereo-to-mono summing cable.
What determines the resistor value that connects the +signal to the signal ground? And honestly what determines the 2 resistors in the +signal path?
I will be using it to sum stereo preouts to a single LFE input on an active subwoofer.