There’s not a lot of information about this headphone in the English-speaking world. How do I know? Well I have tried to look for references with little success.
Edifier seems to have a reputation for offering a good bang for your buck. They have a selection of multimedia speakers, and their H180 and H185 earbuds seem to have a good following in the earbuds lovers community. I read enough about H840 to pull the trigger on one. My flatmate at the time got one as well, in dark blue. I didn’t pay much attention to it until I found a nice braided cable that’s just laying around unused. I decided to recable the H840.
This cable has a measured lower resistance (0.86 Ohm) and capacitance (65pF) compared to the stock cable (1.43 Ohm and 194pF). The sound became more open and balanced. I felt it was too bass-heavy in stock condition. I realized there is some potential in these headphones. They are made with good quality material, but their clamping force is too strong for my big head and their earpads are halfway between on-ear and over-ear for me.
I’m really happy with the results. To some, the above will be just pseudo-science at best. But these mods are totally reversible in case you want to return it back to stock, or you don’t like where the last step of the mod is taking you. Feel free to experiment. In my case the H840 now is more balanced, has more detailed, and pleasant to listen to.