Correct. If you don't EQ the fronts and rears separately, then they are the same audio signal pair, with their relative volume controlled by the fader.

I never used my fader and it was always set to the center position. I used my gain adjustments on my amplifier to balance the difference between front and rear speakers. I found that even with passengers in the car, I never changed the front/rear balance.

So what I chose to do was to run both the fronts and the rears off of the front pair of outputs, and run the subwoofer off of just the rear pair of outputs. This now allows my fader to work as a "subwoofer level control".