you want the countour on sub set to zero and the sub level set to flat ( zero ) when you measure each speaker, you use the preamp volume control to get 2/3 above flat.
you adjust countour and level LAST after getting the EQ on both speakers correct.
so for your example of 76 db which is + 6 you would cut by 2/3 of 6 = 4, so reduce using the corresponding trim pot on back of speaker
in this case rotate the trim pot counter clockwise. go thru all 11 adjustments and rerun. DO not attempt perfectly flat.
after you do both speaker EQ i suggest adjusting countour to .7 which is typical audiophile flat tight bass. Play some music with decent bass energy... Ray Brown - Soular energy is superb for this...
adjust countour to taste and room, my 7 countour is set at .75
next adjust the subwoofer level during the bass scaling solo in the Vandertones disc, you are looking for cohesive, smooth, no peaks and valleys in loudness as it scales up and down....you do that by ear
enjoy
in my opinion, you have one of the best speakers on the planet !