Found a great article with an in-depth explanation of the mythical “slam” feature on 1176’s. In short, pressing all the ratio buttons in changes your ratio to 10:1, but with lower impedance seen by follow-on stages.
The 1176 is a FET unit dependent upon a bunch of design considerations to make it perform in a linear manner. Using slam mode introduces non-linearity to it’s operation. I guess that’s why it’s difficult to explain exactly why slam mode is so awesome.
The original article is linked here.