Let's take the same floorplan for both cases.
You have a top floor corner unit 2LDK where the living room is the corner surrounded by bedrooms. Only neighbours are to the north and west. If you place a home theatre system with a subwoofer and decouple the subwoofer so that it doesn't vibrate the building structure. Will 80-90dB cinematic sound be noticeable or a bother to neighbours? Lots of acoustic panels, mass loaded vinyls and bass traps used to isolate the air vibrations and sound. In a corner unit with no shared walls with neighbours from the living room, how much dB from the subwoofer and speakers would it take to be a bother to neighbours downstairs? At 80-90dB, it already sounds like a cinema or a live concert. Are neighbours downstairs really only hearing sub 40dB? which is almost as quiet as a library while you are upstairs enjoying home cinema?
From my research, flooring in reinforced concrete and heavy steel buildings usually reduce the sound by 50-60dB.
Link below shows example floorplan with circle outlining where the home theatre setup is.
by RenTraveller