Yes... but it is a symptom fix (and gives only slightly better results), not addressing the root cause... which probably cannot be fixed. It does not change the output signal of the DAC chip, only the OpAmp stage is changed and this never has any major impact (unless you run into clipping etc).
For a number of reasons his exact method cannot be applied here but I might try what's actually possible on this board. I'm not overly optimistic but we will see if that helps (significantly).
A smoother IMD+N orTHD+N vs Level plot does not mean there is significant less distortion of the presented kind. It may just mean the distortion is more constant in absolute levels, similiar to general circuit noise. And that more constant (=humpless) distortion base-line might be higher than the noise level. The guy didn't even check the spectra, let alone the residual. Looking at the IMD+N or THD+N vs Level plot is not sufficient.
BTW, the easiest way to drown the hump visually is to make a noisier output circuit. Then we'll have a lower SINAD but no apparent hump anymore (distortion hidden in the noise).