I've recently encountered the Tech21 Sansamp GT2. From what I've read and heard from anywhere, its basically a preamp in form of a pedal. How does this work, basically? Does it bypass the preamp of the amp itself, or is it like another preamp in front of the amp used?

And is a preamp a necessity or just something someone could live without? Because I've learned its pretty good at keeping a consistent tone from plugging into an amp or even recording.

Also, how does this Tech21 Sansamp GT2 score against any other preamp?

Thanks! Noob here