That's really good to know. Why not just make 30 your minimum then and use it like that to get realistic results?
its just not that low of a dynamic - brass tone changes dramatically from pp to ff - it's not just a matter of volume. I don't think I need to explain the irony of your user name asking me that.
But to clarify:
you can reduce the volume of a horn playing at fortissimo all you want, it'll never sound like pianissimo
you can increase the volume of a horn playing at pianissimo all you want, it'll never sound like fortissimo
CSB has absolutely stunning crossfades of the higher dynamics - but very little ACTUAL low dynamics to work with, sounds dull and low volume - rather than golden and mellow.