Compared these to the HD600 very briefly the other night.
I think some other people mentioned the bass sounds a little disconnected and the treble isn't quite smooth (sounds like there are some peaks that come across a little unnatural) and I agree with that. The HD600 sounds considerably more linear with some sort of crazy magic in the midrange that just sounds right, for lack of a technical description. Although subbass is rolled off, I didn't find myself missing what the K371 offered in that area.
I wish I could explain the feeling of "natural" that the HD600 conveys. There'll be a technical explanation somewhere....just the right peaks in the FR, adhering to the appropriate targets....but it's crazy that a 24-year-old headphone can still go toe-to-toe with the most well-informed headphones we have today.
The K371 is great. Nothing (detail, transient response, timbre) felt lacking enough to bump it against anything under $1k. I know the measurements reflect this, but it was really cool to analyse the differences between the two. It helped me to appreciate both the HD600 and K371 even more.