Apologize that this is slightly off topic; responding to question above. My thoughts on MDR-MA900 build quality (not in priority order):
Top Five Positives (IMO):
1. Very lightweight and comfortable overall (and I really like the sound) - could be a portable and wouldn't look dorky/bulky. Very light clamping force, but the seal seems ok (I can't tell about leakage or isolation .. I'd guess average.) [EDIT: These are open-back design, called an "Open Air" design, so I would expect some compromise in leakage and isolation.]
2. Cloth ear cushion, but not velvet or velour. Headband is small but comfortable - cloth covered foam of some sort; not bulky or heavy at all.
3. The ear cups are not huge but completely surround my ear.
4. The part that holds the earpad bracket to the headband (the yoke) feels like aluminum: light but sturdy. Kind of a matte finish so doesn't show smudges much. "Hinges" seem good (not really hinges in the sense of folding up)
5. Driver housing feels like it wouldn't dent very easily - it is a sturdy plastic, I think. Also hides fingerprints.
Top Five Concerns (from an imagined sturdiness point of view, not due to any actual problems experienced in my short time of ownership of 1-2 weeks):
1. The cord is of moderate length (a little too long for portable use and a little too short for studio use, depending on the set up) and is thinner than average. Doesn't tangle, though. The 3.5mm connector is average, and an attractive metallic finish (IMO)
2.. The joint where the cord attaches to the driver housing appears like it might be on the fragile side - a good bump, if there is such a thing, might have bad consequences. The cables are not detachable.
3. The ear cups are angled toward the ears at a degree off perpendicular, so the back edge sticks out.
4. The ear cups are quite flexible so you get a good fit, but they move in a couple of axis, and I don't know how much torque they could take without problems surfacing. Like if you jam them in a backpack kind of a deal.
5. The part that is exposed as you slide the brackets in and out to adjust sizing/fit seems to be plastic and not all that robust.
On balance, I'd say it is six of one and a half dozen of the other. I think probably fine for home use at a desk. At a rowdy party or frequently stuffed in a backpack, not so much.
Back on topic ... these cans are VERY light and comfortable, and the 70mm drivers sound VERY good.
Hope this helps. I'm glad I bought them .. much different vibe than what I'm used to from Sony. In a good way.