Putting aside the error in Stereophile measurements that show a non-existent bass boost, Showroom sound was kind of invented by Klipsch with hyper rise in tweeter response. That brings out brilliance with the highs clearly standing out. In turn, it makes neutral speakers sound muffled in a showroom AB setup. Bass boost can be considered a secondary aspect of this but not nearly as much as the treble boost.And another, what we see at the Buchardt is NOT showroom sound, is the opposite.
Showroom sound boosts this area like this: