The pedal doesn't "react with" the amp you plug it into. If you want to know how the Ampeg sounds when fed signal from the pedal, basically the Tone Hammer can provide boost (which can overdrive the input of the Ampeg) and it can provide its own distortion, making the Ampeg sound even dirtier and more driven.
Lots of users plug the Tone Hammer straight into a power amp; Aguilar has posted several times on here that it was designed to be able to work that way.
The Sansamp is also able to drive a power amp no problem; the Sadowsky, I'm not sure. You'll want to look up threads that mention the Sadowsky pedal and see if the owners comment on whether they have driven a power amp with it.
Check the article on preamps in the FAQ in my sig for more info.
