Hybrid Pads really helped too with the frequency response, at least in my opinion. I bought a used pair of Nighthawks that included Hybrid Pads that completely changed the sound signature for me - making the bass cleaner and the mids less sucked out.
The interesting thing is once your ears/mind adjust to the sound signature then vocals actually sound really good on the Nighthawks. At first it’s wonky but a little time helps your brain adjust. I really like my Nighthawks even if they aren’t as good as many Focal headphones which are clearer and brighter.