Does You Subwoofer Settings ??

Room acoustics issues are static, more or less, and variances are most likely in individual recordings, particularly if the differences are in quality, e.g. definition not just qiantity. Also, If you are listening at only 75 dBA, you're also well within Fletcher-Munson loudness curve territory. The ear at that loudness is decidedly non-linear and changing the volume even a few dB will change the ears linearity, especially ar low frequencies. 

You never mentioned what your main speakers are! What are they? Is your system 2 channel or home theater?

I find myself tweaking my sub settings frequently. I don't use any measuring devices or room calibration, just adjust by ear. Annoying, but ultimately satisfying.

My system is new that is my Amp of approx 7 months. I had a Raven Audio Osprey Tube Amp and stepped up to their Reflection and have had Raven Audio Corvus Speakers for 5 years ...Last year I had speakers on steel stands and I finally built wooden box stands with Granite Base and granite top plate and it allowed me to hear the real music I have been missing for over 4 years..And now with Reflection a even larger sound that never knew could existe to my hearing..So at 73 yrs old I am really enjoying this new hobby for last 5 years..Some small adjustments with Subwoofer and maybe few tubes and believe I will be very happy.

I just like to sit back with Tidal Selected songs for about a hour and make no adjustments ..This makes me forget about my ringing tinnitus and this is about Max time I can listen before my hearing starts to become over sensitive ...

And take the songs that cause boominess put them in separate Tidal folder and adjust them and play them later...