I suppose we've discussed this topic thoroughly in the past, but my thoughts returned to it while practicing this evening. At my age and skill level, the ergonomic qualities of my instrument seem to make a noticeable difference in the quality of the music I produce.
My flugelhorn and cornets do not fit me as well as my trumpets. Among my Bb trumpets, one seems to fit a little better than the others. Location of the third valve slide ring and space between the top of the third slide and the bottom of the bell seems to make the most difference, along with the distance from the valve block to my face.
The effect I notice is a light quaver that seeps into my tone and fatigue that develops in my messed up right shoulder. Do any of the rest of you experience something similar, and does the instrument you play make a difference?