Amplitude adjustment hotkey?

You can do this already by creating two Favorites, one for +1dB and another for -1dB. All you have to do then is assign keystrokes to each of them. If you use the - and + keys though, you'll lose zooming. If you really want to use those keys, then you'll have to either lose the zooming, as mentioned, or use them with a modifier, like the shift key - so shift and plus, and shift and minus. The only other thing you will have to do, to make sure that the attenuation only applies where there's a selection made, is to edit the Favorite's Amplify line so that instead of being Selection, it's Relative. If you don't do that, you'll always have the selection you originally made as the bit that gets amplified, which is almost certainly what you don't want!