Summary: 70mm drivers, fully open design, premium materials, and simply the best comfort of any headphone at any price. The MA900 has many things going for it. The sound signature is a little laid back, but ever polite. One would think that a 70mm driver could provide a hearty slam. This isn't the case -- sub-bass is almost nonexistent, and midbass is inferior to that of a Grado. Decay is slow on the MA900, so the midbass isn't super-crisp.