Episode 3 at 23:26.
Characters enter office of jazz nightclub and there is a euphonium hanging on the wall.
Lighting is dark and scene is quick so maybe better eyes can tell what make it is.
There are also pictures of musicians all over the walls (also a little hard to make out with the lighting).

"Cowboy Bebop" is based on an animated tv show and may not be for everyone.
However the music is prevalent throughout in the live action series and so far all of it is well good.

Michael S.
Rock Hill, SC