My take on Audyssey sub eq.
It told my my subs were too low, and when I checked with its level matching on screen, it had them showing about 70db, but yet it set their levels to -8.0db in the menu. So, as usual, I ignored that. I ran the MLP measurements and then calculated, adjusted gain, and the re-ran until both subs were set at -6.0db. Once you get the MLP right, it takes the other 7 measurements with the subs acting as one. Once I finished, I broke out my db meter and once again, with both subs active at the same time, it set them about -5.0db lower than the other speaker. The nice thing is you can adjust them individually, or both on as one. I see no need to adjust them separately because the reading you get it lower than it should report because the other sub is not running.
At the end of it all, I found I needed to boost it 5db in the level menu to get them to match the other speaker. This left me at -1.0db for both subs when they were playing in unison.
Not bad, just added a little time to get both the gains right where the subs measured closely in output at the MLP.