The Sansamp is a tube emulation device. The TH is not. With the AGS off, and the EQ flat, it changes the tone very little if at all. So it's strictly EQ. Engaging the AGS with the gain all the way off imparts filter which seems to roll off any upper treble, but even that is fairly subtle. The AGS does add overdrive as you turn up the gain, and it changes how the EQ knobs work a bit, but it still sounds like your bass. The Sansamp stuff on the other hand makes everything you plug into it sound completely different if the blend is turned up. Two very different approaches.Correct me if I'm wrong, but there's no way to use the EQ on the Tone Hammer without the DI coloration (like you can do with the Sansamp Paradriver)?
Check out the videos of the TH at the Aguilar website. Most of them are recorded with the TH off and then engaged so that you can get a feel for what it does.