Steinway Model B vs Model D
The B and the D are Steinway’s two largest grands, and the choice is almost entirely about the room.
The difference
The Model D, at nearly nine feet, is the full concert grand. The Model B, at just under seven feet, is the largest piano most people can sensibly keep at home. The D has more power and more sound; the B has most of the character in a piano you can live with.
Which for a home
The B, in almost every case. A Model D needs a very large room or a hall to be heard properly. In a normal home it is too big and too loud, and you lose much of what you paid for. The B is the top choice for a serious home pianist.
Which for a hall or studio
The D, where the room can take it. It is the concert instrument for good reason.