Another both.
But the music or song comes first. If I want to hear Spike Jones and his City Slickers, then I grab the cassette and put it on. If I am wanting Beethoven's 7th, I start chosing based on where I am at (bedroom, TV room) and decide between CD or Vinyl and version.
In short - for background, its strictly the music; for a musical experience, the system figures in.
And let me note, too, that I am not trying to down play the importance of background: in visual terms, the color of the walls and a painting/print can make all the difference in any room/office.
"nuthin like the mounted head of a Jack-o-lope to give a room pu-zazz"