Yes, with the old FW, turning Audyssey off delivers the correct level to the SW channel per the calibration. If you enable any of the Audyssey modes, the SW channel incorrectly receives a decreased signal level resulting in -9dB SPL decrease. I recall all that was needed to bring it back to the correct level was to manually add +9dB to whatever the calibrated level is.
So if EQ off, leave SW dB level at calibrated.
If EQ on (any mode), add +9dB to SW channel's calibrated level.
I remember I did measure the -9dB drop-off with my SPL meter when enabling/disabling Audyssey EQ, back before 2 children and time for such things.
To my understanding, this bug was corrected by H39 FW and possibly even an earlier version.