Every amp that has a tube has a bypass switch to switch it in and out.
You should be able to tell the effect it has on your sound. Switch it out when you don't want it.
The "Drive" control on the Carvins is a well defined and controllable distortion that has nothing to do with the tube.
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"The good thing about science is that it’s true whether or not you believe in it." - Neil DeGrasse Tyson 2011
