If you don't have a sub I am surprised you get an option for setting the speakers. But since you do, set it to large, and then you'll find out what the bookshelf 55hz speakers can do, it might not be too bad except for some movies. If it sounds bad turn it down.
I have some little Infinity bookshelf speakers and they have "magic" clean tight clear bass for music.
I've heard other small speakers where you would swear there was a sub hidden somewhere. Depends on their design and the room I guess.
Music, more music.