I know exactly what you mean, had the same problem when i used my headphones for more than 30minutes. After a few suggestions from friends who work at the studio quite often with headphones, i ended up buying the AKG K701. Its a realy fantastic thing, soundwise and also comfortable. I wear it sometimes for more then 2 hours and had never problems with aching or pain.
Sure, you dont want to buy another one since you just bought a Audio-Chi… just if you have to find a solution that works for you and your ears, give the AKG a try.
Greetings and have a nice NYE
p.s. you can see a pic of my AKG701 on my profile