I used to have a pair of Koss Portapros before I got my M50s so I was interested in having better headphones than my usual phone earbuds. After reading the reviews here, I managed to get a used pair of M50s for £85 which seemed like a good bargain to me. After around 2 weeks of stretching out the headband and getting used to the flatter sound signature of these as compared to my earlier (bass-heavy) Portapros, I have to say that my lasting impression is one of awe at how these manage to tick all my boxes.    They're really portable, fold up easily...