I use it for one week at my place of work.
This headphone is a reference to psycho-acoustic studies (re-recorded signals by listening to binaural dummy head).
Since there is no longer, he was first replaced at our catalog by HD 580 Precision and now by the HD 600 and HD 650.
I could listen and compare only the HD 580 and HE 60.
The two offer the same physical comfort headphones open high-end Sennheiser.
It feels to have nothing on the ears.
What is impressive with the HE 60 is the accuracy of resolution in all frequency ranges at a time. This makes it very easy to separate the different components of a signal.
Its super impulse response is unique for a headphone. You feel all the sounds of acoustic guitar, or percussion.
It was also felt that the signal comes from a further source close to the ear less than the 580. The result is better stereo separation.
Should do more listening tests with other brands and other models to justify the price of € 1,000 and disadvantages may represent the use of a dedicated amp 540V and polarization of the membranes.