It is a picky headphone, it's more revealing than most headphones in it's price range. Lets just say if I had only the Magni as an amp when I got the K612, I may of preferred the MA900 to the K612. The K612 actually isn't that demanding of power, it just needs enough(basically a desktop amp), what it really needs is synergy. Proper amping in the case of the K612 is all about synergy. With the right synergy, it's more musical, engaging, realistic, and natural sounding than the MA900. It sounds it's absolute best on aggressive and dynamic amps imho and it seems to prefer tube or hyrbid amps to ss amps.