Here's what I get with 3 extra bits ERES setting on the Acquire menu with a 1k signal that's actual highest harmonic is 2nd at -90dB or so:
View attachment 1387363
So that's become -52dB or so, about 8 ENOB rather than the 11 you'd expect - I am not sure ERES works for Math functions really. Anyway what's to be expected for 8 bit 'scope.
I turned on lots of averaging to see that nice flat noise floor, and I'm using flattop window as we are measuring peak heights.
