TubeNet

To make a long story short, I'm currently in the hunt for a smaller mouthpiece to help with solo and chamber music playing, since my current equipment is a Wisemann 900 and a Blokepiece Symphony and I don't have a bass tuba quite yet. In a large ensemble, my current setup is fantastic, but for smaller stuff, not so much. With that in mind, I've been trying out a Parker Titan with the same rim and shank on my Symphony. After a week, I've noticed a few things. From a physical standpoint the Titan paired with my current rim is extremely comfortable, perhaps the most comfortable mouthpiece setup I've used. From a sound standpoint, both my professor and I like what is being produced, however, there is a constant fuzzy sound that I can hear under the bell, and can also be heard in the audience. I'm wondering if that might be caused by using a Symphony shank, rather than the Titan's proper Titan shank?
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The only way to know for sure is to try one out and see what happens. Why not call a dealer and see if you can get one on approval?

Surely using a shank that doesn't fit the cup 'properly' is bound to cause issue?
Have you tried using the correct shank...? =)