I will go point by point, so sound, comfort while wearing and finish, but first I think a little pre is necessary.
These are not the standard general music listening headphones you would be buying to use every day at any given time.
The HD681 are made to let you analyze music you make or mix yourself as main purpose, therefore they will feel different under several aspects.
Don't think of the differences being a down side, that would be a mistake.
Now let's get started
Sound: 10+
First test made with my phone just by playing mp3s.
At first I was not impressed but then I thought "Hei, these are different a whole lot different then usual headphones, let me tweek a bit the EQ".
The result is amazing, once you adjust the source to the headphones the sound changes totally and you will start to hear all the frequencies and the dynamics you've never heard before. All the instruments will be there easy to be pointed out but still sounding as a whole.
Still this is mp3, which means a lot of compression, so I tested them with some mixing uncompressed samples I had on my laptop, and there is when these littles babies show their best skills.
At slightly higher volumes, in mixing sessions you will be really able to judge and understand your work better, and thanks to that the final result will automatically be better.
Dynamics, volumes, frequencies, you will hear everything crystal clear as you've never experienced before.
My score for the sound is 10+
Comfort while wearing: 10+
Not much to say here, the pads are big enough to get around your ears easily, as the speaker is 50mm.
They are extremely nice to wear, soft, not too warm at all, especially during long sessions, They don't feel heavy thanks to the support on top of it which is very flexyble.
Basically you can wear them for hours and you won't be bothered by them.
Size-wise, yes they are quite big, but hei, the speakers are 50mm you should take some size into account, and anyways this is irrelevant to me personally so no problems there.
My Score here is 10+
Afwerking: 10+
Side supports and pads backpanles are plastic material, very well finished and painted, no imperfections.
The jack is just a connector with a well made rubber shielding around it, you have 2 separate jacks cable of different length, flexible, resistant, and if you stand up and walk away you don't break anything cos they will just detach.
Rubber-ish material made the top head support under the 2 metal rods, light flexible comfy and nice to the touch.
My score is 10+
All in all my experience with this product has been great so far, and I am totally happy with this decision since I was pending for more expensive headphones of the same kind.
The only thing I can say is "Best Choice Ever".
Y'all enjoy.
Thanks for reading.
Cheers