Modelers are supposed to model the preamp of different amps, so... When using a modeler with a tube amp, you get the "real" tubiness from the power amps (they have to be pushed though). Most modelers sound like butt when used along with a real amps preamp as well. It can work, but you have to find a happy medium between the modeler's and amp's EQ settings. It all depends on how willing you are to work for your tone, and what tones you like.

Personally, if I'm playing through a good tube amp, I'm not about to screw with it's already great tone by adding some silly 'modeler' into the mix :rolleyes: