Trumpet
You are correct the Trumpet is definitely broken. It is muffled at times to the point of it being muted out entirely. I too adjusted all my settings but like you it made no difference. The sharp distinction of a note snapping off is totally gone to the point that often times it runs them together. It’s almost like a badly synthesized old 32 bit game. The bell and the flute are fine. Won’t sell many horns with them sounding this way that’s for sure.
You’ll be happy to know this has been reported, acknowledged and is being worked on.
Follow that thread here:
https://forum-en.gw2archive.eu/forum/support/bugs/Mariner-Horn-Sound-Error/first#post3531521
Bump… would be nice for this to be fixed. How much will it co$t?