upgraded from Sb2 to FLX6-W

when choosing the 1 channel that you want to listen to for cueing, the SB2 allowed for a 70/30 blend ratio in the headphones while only choosing 1 channel to listen to. Basically, I taught myself to blend without monitors. 

with the FLX6-W, it has headphone mix and volume knobs but you hear 0 of the outgoing track unless you click BOTH channels to listen to. And then its just too loud. the headphone mix knob only makes the track louder in the headphones rather than a adjusting the level of sound coming from each channel for purposes of cueing. 

does the flx6-w have a way to adjust this ratio? btw it's not a split headphone(I.e.left/right), that i am trying to achieve. I am just trying to make the incoming track louder than the outgoing while hearing both signals in the headphones.

thanks in advance