Thanks for the tip about the HE-6SE, I'll keep an eye out when it's on sale again.
Right now I still can't believe the change in sound, no more weird mid harshness and it's more open/smoother and still have that amazing bass.
That weird mid thing was also affecting some lower kick sounds,can't really explain but it had some plastic quality to it, which is now completely gone.
(I'm a nitpick in these things I now).
I was at my work office but couldn't wait to get home to get back to listening again.
This completely rekindled my interest in hearing more music with my HE-400 again. And also interesting in maybe looking out for some other amp/dac.