AKG is not what it was in the past, they don't evolve, they use the same driver in all of the 7xx series of headphones with just small difference in tuning, the k812 is bad headphone for the money, it is HD800 response but not successful one,
with lack of innovations and the involvement of the harman company the fall is something to be expected
K812 is a very good headphone. I've always found it to be superior than HD800 in many aspects including macro detail / instrument separation / sound tracking. It's also among the most neutral sounding headphones in the lower midrange and bass unlike the HD800 which is markedly lean sounding (leading people to find the right high Z amp, then simple mod, then multiple mods, you know...)
All in all, I also find the K812 to have a more natural fit on the head. The earpads are more cushiond and the headband is very even.
It's also slightly smaller overall. HD800 is very big so it extends beyond what most people are used to.
HD800 provides a slightly bigger stage and more microdetail / texture.
With regards to the K7-series of studio reference headphones. I've had two K702 and still have a K712.
They are very capable headphones that were tweaked quite well through the years.
Sennheiser as a company is driven much better than AKG. That plays a big role here.
I don't think AKG problems are related with their headphones.
As far as I know they moved production to Slovakia and China.
I've had 2 AKGs K702 made in China, both well made and both showed proper channel matching on measurements.
I still have 2 AKGs made in Slovakia (which by the way is about 60km away from Austria) and they are both well built too.
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