They're suprisingly good. And i'm pretty fussy when it comes to headphones.
And they're not just "earbuds" these actually form fit into your ears, and in doing so, are able to use the airight passage between the drivers and your eardrums as an enclosure, of sorts.
It's unreal.
Their high end drivers, i think they're e5c? are actually on-stage monitors for musicians. And instead of using the one-size fits all foam or rubber earpieces, you can get an actual molded earpiece by visiting a doctor or hearing aid specialist.