I owned HE-400, HE-500 & now HE-400i.
HE-400 were NOK for me because of (too) recessed mids, I really loved the sound of HE500 but I simply could not live with them : too heavy & too much clamping.
I bought HE-400i thinking about an upgraded 400 (without the hole in the mids) but to me they sound like another headphones, not related to HE-400, nor to HE-500 to be honnest.
Comfort put aside, I much prefer what HE-500 bring on the table.
I miss air & excitment with my...