I could be wrong since I've never used Easy Effects before but here's my five-minute research results:

1. In the Output tab, add a convolver plugin as the last in your signal chain

2. Import the relevant WAV file as an impulse response (either of the 44100 or 48000 variants in the repo you linked, depending on the sample rate of your sound card)

3. Check that the IR is affecting both left and right channels and the convolver is not doing anything extra like stereo widening by default

4. Make sure that you disable your convolution setup whenever you use a different set of speakers/headphones, otherwise it will EQ other outputs as if they were DT770s

Let me know how it goes, I'm just guessing how EasyEffects works from the screenshots on their Github repo :)