mp too quiet?

in the first two bars of the uploaded score, the trumpets and tuba are inaudible to my ears over the french horn. Even with the timpani muted I still can't hear the tuba; it works fine if I raise everybody to mf though, then the balance becomes better (at least to me).

EDIT: for some reason this post got posted twice, the correct post (with the file) is here: https://musescore.org/en/node/365365