ye, true about the 990. with them on a moderate volume, i can pretty much hear everything going on around me. i prefer this, as wearing closed cups for a long time makes me feel a bit disorientated, especially the moment i take em off. my housemate got the 770 pro, and he's happy to use em for monitoring as a live engineer, so yeah, they're pretty closed.. no idea what's the difference between the 770 models, but if you wanna go the extra money mile, get the 880. so lush, and you can even colour code them at beyerdynamic's website. very pimp!