Sennheiser Momentum Break In Time

Just bought a pair of Sennheiser Momentum on Ear headphones, which I quite like. Wondering what others have experienced with break in time. I know my HD650's took a long time. Thanks.
After 36 hours plugged into the radio, they already sound better.
I have not noticed much break-in difference with my over ear Momentums I bought a few months back.