Oh, what a difference a year can make. When I bought my Sony MDR-V700s in early 2004, the V-900s cost twice as much (over $200), and have identical specs, so I went with the V-700s. A year later, Sony has replaced its entire line of headphones, and you can now pick up the V-900s on the cheap. Are they worth it? Read on.
One of the major differences between the V-700s and V-900s is the design of the ear cup. The V-700s are “supra-aural”, which means they sit directly on top of the ear. The V-900s, on the other hand, are “circum-aural”, meaning that they wrap around the ear, while putting no pressure on the ear itself. All supra-aural headphones pressure your ears against your head. How much depends on each individual headphone. Probably the most painful example of vice grip headphones are the Sennheiser HD-280 Pros. They use immense clamping force, which provides incredible sound isolation. The only problem is, in my opinion at least, they are wearable for maybe a half hour. The V-700s are not that bad, but they tend to get very uncomfortable after about a three hour stretch, which is the reason I decided to make an upgrade.
Other than the difference in design, the rated specs for the V-700s and V-900s are identical. They are both sealed, dynamic phones with 50mm drive units, though the ‘900s use Sony’s more advanced Amorphous Diamond Evaporated Diaphragm. The impedance for both is 24ohms (though the ‘900s have a “@1khz” qualifier to that), and the ratings for sensitivity, power handling, and frequency response are all identical at 107db/mW, 3000mW, and 5hz-30khz, respectively. (For explanations of the terms and measurements above, please see my V-700 review here.)
