Quote:
Ultrasone pro 550 has much more flatter bass response than pro 900 and highs are rolled off so it contributes to the "flatter" sound impression. At first pro 550 was very very aggressive, but burn in was spectacular from up front to bass heavy and than the truth which I end up not liking.
Wow, that must really suck having cans burn into a sound you dislike. Kind of like loving listening to them but in the back of your mind, you want to preserve the driver a little longer.