I think that the choice of speakers is better if someone must choose only one system...But you are right they are complementary, few headphones can rival speakers of the same level quality in depth imaging and soundstage, and yes few speakers can rival headphone in details....
For the AKG the most important thing for me, is the damping method (sorbothane inside and outside)+ also the stones(agate+shungite) I use to improve the soundstage, and cutting the plastic grid,removing the wool;but at the end the cleaning of the electrical grid is another big improvement because the hybrid AKG is very,very sensible to the source and to the floor noise level, at the end my AKG crush all my headphones totally on all count : the he 400, the Stax SR-5, the lambda nova, the beyerdynamic DT-150, it is impossible for me to listen to them now...I apologize if I was rude, I am sure that you know what you speak about, but I know also something...Thanks very much for your reply and interesting participation...and I give to you my best for the Christmas to come and for all people here also....
A last remark, the most upgrading effect in my audio life is this cleaning of the electrical grid which I am advocate here,the AKG was transformed by that on all count, especially the depth imaging improvement, the near spherical soundstaging effect, and last but not least the really natural sound that comes from it at last because of his mids frequencies flowing accent... There is better than the AKG,(your Stax are certainly better driven by BHSE) but probably not under 1000 bucks, and the rendering of voices is so detailed and perfect that even higher than 1000 I think it is not evident to replace them... No headphone is perfect but for 100 bucks, I cannot imagine to upgrade them...And remember that this thread is not about the better in an absolute sense,but about what we can do to approximate the best there is with intelligent choice of elements and methods to improve them all...Newcomers will appreciate the possibility to have this experience at a reasonable cost... When I come here 7 years ago I really think that under 6,000 bucks, all choice were too short and not sufficient for the TOP audio experience possibility with dac,amp,speakers and headphone package... I dont think so now...