tl;dr – They are awesome!
I’ve spent the last two hours working at my desk and listening to my music collection via iTunes Match. These new headphones have a quality that is hard to describe to someone–mainly because I don’t think I have the right words in vocabulary. The sound is certainly clear and well-defined considering the source and my local PC’s sound card.
The HD280 speakers are amazing for the size (watch a video if you want to learn more) and produce what I have to call a “compressive bass” sound. Instead of bass ‘hum’ instead your ears can feel the air pressure changes therefore the bass has a tactile quality. I think this comes from the way they encompass the ear and truly isolate the air gap between the speakers and eardrum. These are the first headphones that I’ll have to worry about volume limits.