You are looking of a "Japanese" audio system. Many Japanese listeners live in small apartments and have to keep the volume down (particularly because they are such polite people). That is one of the reasons they put gigantic horn systems in their small listening room--horns sound great at low volume). Unfortunately, good horns don't come in the price range you are shopping.
In that range, I would look at Audio Note speakers, old LS3/5a's, ProAc Tablette or D-2, or Rethm Bhaava. These sound quite good at lower volume.
I know it might seem a bit counter-intuitive, but, large dipole panel speakers are also contenders because they can be played a little bit louder than non-dipole speakers with less sound spilling outside of the listening area between the speakers. The front and back wave are not in the same phase, so bass energy tend to cancel at the sides of the speakers. I was shocked at how much of a difference this makes as to sound encroaching on other rooms when I went from dipole electrostatics to dynamic drivers.
