If you have problems with the comfort, adjust the "wings" of foam and replace the earpads. Here is a link to popular earpads for the 668B's
https://www.amazon.com/Cosmos-Velvet-Replacement-Cushion-Headphones/dp/B00KLPRQMO/ref=sr_1_7?ie=UTF8&qid=1517850067&sr=8-7&keywords=akg+earpads