Hey HooStat, I did that EQ for you....so you can use the EQ on your RME, so that's 2 Shelf Filters and 5 other EQ Filters, that was all we were allowed to play with for this EQ. As I said, this is taking Oratory's measurement of your Neumann NDH20, and then I used REW and created filters for it manually. I think I got a pretty good result with the EQ in terms of it tracking the Harman Headphone Curve pretty darn close over the whole frequency range.....if I was allowed to use more filters then I would have smoothed out the frequency response of the bass & mids a little more, but for sure it's a smoother response with less overall peaks than what you have at stock without any EQ. So here's the result along with the filters in the following pic:
Neumann NDH20 EQ:
View attachment 83752
Don't forget to add in a Negative Preamp to the above filters,
you'll need -5.1dB preamp.
You can see that Filter #1 is the Low Shelf Filter, and Filter #7 is the High Shelf Filter. If you feel like the headphones don't have enough air with the EQ then just don't use Filter #7. It'll be interesting to see what you think to the EQ, given what the EQ is doing in the bass & mids then I think your headphone will be less muddy and have greater clarity, but just have a listen & see what you think.
The blue line is the Harman Headphone Curve. The "highlighted" line in red (most visible) is the frequency response
after EQ. The faint red line that you can barely see (in the back ground) is the original frequency response of the headphone. And finally the turquoise coloured "area lines" is showing the "filters effect". But the one I mentioned already, the "highlighted" line in red is the most important as that's showing the final Frequency Response of the headphone after applying the EQ.
And the following is a pic of the Neumann NDH20 EQ in Equaliser APO, so you can see the EQ curve in the Analysis Panel at the bottom of that pic....you can see that the EQ curve is very smooth as I didn't use high Q filters, so I think that's a positive attribute that the EQ curve is so smooth.....in my experience smooth EQ curves sound better, and I think it's accepted knowledge too (less ringing & other artifacts I think):
View attachment 83754
EDIT: double check your inputted settings in your RME against the filters I've listed here......in my experience it's so easy to do a typo whilst reading or entering the filters which will end up with an incorrect filter curve, so I'm kinda paranoid and triple check my filters I've entered to make sure I didn't do a typo, lol!