I play the sousaphone in a New Orleans Brass Band - I need a mouthpiece that will enable me to give a big sound. I have been using a Sousapower 3 and was getting fabulous results - these mputhpieces really do deliver their promises. I selected the Sousapower 8 as it is slightly larger in cup diameter than the #3 which I hoped would make hitting the very low notes a little more accessible. It also has a slightly smaller throat which gives a little more control.
It works - its fabulous - I used it for two tough gigs over the weekend and it really delivered - big sound, good attack, thick and heavy 'meaty' quality to the sound, the cup does open up the lower register. The sound is big and powerful but at the same time under control. In addition, I didn't feel quite the same embouchure fatigue as I was expecting.