Well we think that after almost 70 years in designing transducers and 40 plus years researching and manufacturing open headphones they know what they are doing.
While I’m waiting for Sennheiser to get parts for my HD700s I’m stuck listening to my HD580/600, and while they are satisfying once I mossy up to their sound signature, IMHO the HD700 pull out all the stops with regards to what I want in sound, openness and staging and can’t help but feel the HD600 series are overall dated in comparison.
I believe those that do not find the HD700s as accomplished as they are may be too accustomed to the “head between the speaker effect” and have difficulty getting at what exactly Sennheiser has achieved with the HD700s.
Yes the HD800 and some other phones are more revealing still but they miss the overall objective, sort of akin to sticking ones ear to a speaker’s tweeter to hear all the detail, same goes for bass reproduction. For example with direct comparison to my Dynaudio Special 25s augmented with my 15” Velodyne equalized for a flat bass response down to 20hz the HD700 give me the same results, anymore and I know technically the bass has been exaggerated. And even though the HD700s are still more or less still typical to headphone staging, more vertical than horizontal, they do come much closer to what I expect from properly positioned speakers than any current phones I’ve listened to, excluding the AKG K1000s or similar, which fail terribly with most other aspects of the sound, but that’s just me.