i've owned both, as well as the very similar sennheiser px-100. they're all quite good and very comfortable (though some may prefer a plastic headband to metal one on the koss), but i end up prefering the portapro--better build, a tad more life/dynamic slam and deeper bass--plus koss gives you a lifetime replacement guarantee. at the street price of $35, i think they're one of the greatest bargains in audiodom.
