Well, I modded my Nighthawk. Two sorbothane mods. I'm perfectly happy with my Nighthawks, but I was...........curious.
I had two sets of sorbo discs, one large and one small. I tried the large 1st...............
Taking everything apart was extremely easy, just take off the pads and remove 4 screws. Once open, I saw the grill and turns out the larger sorbo disc covered it completely. So immediately I'm thinking I'm about to turn my Nighthawk into the ultimate closed headphone right? Well.............. Not exactly. Leakage was improved, but not to the point where I'd wear Nighthawks in a library.
I decided to compare the modded Nighthawks with my current go-to portables, the Audeze EL-8........
The clarity was improved, and I mean noticeably. Obviously more treble, clearer mids and low mids, less bass. Clarity was much better than the EL-8, HOWEVER, My EL-8 had a better soundstage and felt more musical and magical.............NOTHING is more musical and magical than a Nighthawk.
Now, my EL-8 is also modded; I put speaker padding under the EarPads to improve the soundstage and it worked great, but the Nighthawks's soundstage was still better before the mod, so even with the increased clarity I considered the experiment a failure because the leakage problem was still there and I lost the soundstage.
Nighthawks are already perfectly tuned, so the best I think you can hope for is not screwing them up too badly.
With that in mind, I STILL decided to try a sorbo mod with smaller discs since I was in a self-destructive zone.
Now the discs weren't self adhesive so I had to hope they were thick enough that the drivers would hold them into place. I think they held because when I opened the Nighthawks again I found they stuck to the back of the driver, even though they weren't exactly dead center like I hoped:
Clarity was slightly increased, but not as much as with the bigger discs. The soundstage was better but still not "magical", so I took them out.
My opinion on modding the Nighthawk? If you love them like I do, don't do it!