If you consider 4'33" (John Cage) to be music, you have your answer right there.
Not music in my book.
Even if not, there are still many examples that can be found. Much of the Hollow Knight soundtrack is pretty quiet (not the boss themes, though), and there's lots of quiet classical music out there. (It's not unusual for classical music to be both loud and soft at different parts; the 3rd movement of Beethoven's 5th symphony alternates between quiet passages in the low strings and loud passages in the brass, at least at first, while the 2nd movement of Beethoven's 7th symphony (highly recommended, one of the best symphony movements out there) starts quiet and gradually builds during the first major section of the movement.
I'm not sure I can look up the examples now but I'm guessing it's got something to do with the lack of a (discernible) beat or percussive elements. Slow strings or pads fade in and out, move from note to note without an attack, and so on. Is that what makes music quiet for you?
But in my case, even arhythmic ambience can be loud. And then there's music that I consider quiet or loud depending on how I listen to it. For example, this one song
can surround me with thundering loudness, but if I turn it down, I hear a calm beat reverberating through the distance.
Anyway, I love *chill* music, and I've never really considered quietness as such. What comes across as chill is of course very subjective... I can fall asleep listening to Insomnium or Serenity in Murder
, but most of everything I hear on radio would be super irritating and difficult to chill to.
Finally, I think this is pretty quiet
. Whether it is metal or just a metal band playing something entirely different is up for debate; a debate I shall take no part in. I don't care about genres too much; my two main genres are "I like it" and "I don't like it."
Warning: linked music features instruments you hate :<