I've put my ZX1 through probably close to 20 hrs burn in and I think I'm ready to sell my AK120. The ZX1 seemed to have opened up in the the mids and highs more. It's not as warm as when I first had it. Listening to the Tumbao De Tamorito track from Open Your Ears album the space just opens up more & gives a more front row presentation whilst the AK120 is probably just a few rows behind.
With my MH335DW the bass seems a little more comparable between the two though which was different from my earlier findings (at least with the Open Your Ears album). I may try different tracks .
So anyone up for an AK120, ping me :D.