Mouthpiece question

[Art Hovey]

Only you can find out for sure. Swap the mouthpieces and see if it makes a difference. I suspect that you listen to yourself more critically when you are practicing than when you are schlepping the sousaphone around, and that contributes to the fatigue. I know I have played quite a few seven-hour dixieland gigs with only moderate fatigue in the chops, but I never could play seven hours at home. Having fun is a lot easier than working.