I have this helmet in recent years. Its big brother the HD650 was already out, but I nevertheless limited to the HD600, a little cheaper. I was based on benchmarks of the music press to make my choice. I bought it to replace an old AKG K242, which also is a very good helmet. I have not been disappointed. The spectral balance is very successful, I do not see excessive brightness as has sometimes been said. The definition is excellent, every detail is audible. The stamps are excellent, silky highs. I especially like the stereo image, airy, three-dimensional. It took him some time to reveal its secrets. Running or simply time to adapt? Its main drawback, in my view, is that it is open-ended. So rather headset to use when you are alone in a quiet atmosphere.