Why magic at 80 db?

The features seem a to run less hot, but still...wow.

observe the same thing on your TV set - the feature presentation will be at a lower volume compared to the ads that come every 10 minutes or so. MAke a note of this the next time you are watching TV (don't touch the sound level on your remote when the ads come on).

IMHO I don't agree with the Fletecher and Munson or Robinson-Dadson effects suggested but I do agree with the possible effects of your drivers not being broken in & your amp-speaker interface.
Additionally, I believe that the sensitivity of the drivers used in your speaker could also be an issue. the drivers are likely not very senstive to very low music signals meaning that you don't get much pistonic action hence not much output SPL from them. 2ndly, even if the drivers themselves were sensitive to low music signal, the cross-over circuit could be attenuating that low level music signal & preventing it from reaching the drivers.
it's quite an art-form in speaker design to make a cone driver speaker responsive to low music signals; most of the speakers in the market simple do not make this grade.
This is where electrostatic, ribbon & planar speakers win big time - the mass of the driver is much, much less than the mass of a cone driver hence the responsiveness of planar speakers (due to sloth I'm clubbing all 3 categories into "planar" speakers) is well-known by almost all in the user community.
FWIW.