Summary: I recently purchased a used metal detector on eBay. The seller included the Sony MDR-V600 headphones, for free. He told me the ear cushions were 'flaky'. He was right. Sony uses a very thin vinyl to give the 'phones a leather 'look'. I took these pads off and threw then away. I guess the ozone outside ate the material.... I then found a seller on eBay that had replacement pads for cheap with free shipping. Yes, from China, where else? I ordered 2 pair.
Summary: I purchased the MDR-V600 years ago and I love them. They were not labled "studio headphones" at the time. They are light, comfortable, and give a full rich sound. I've had my pair for more than a decade and they've held up perfectly with standard use. I missed 4 phone calls already today listening to music with them so I would have to agree that there is very little outside sound intrusion.
Summary: These headphones are the best I've worn yet. Admittedly, that's not saying much, as I've worn very few Audiophile-or-Studio-Quality headphones. However, I think they definitely can compete.
My only gripe is the pleather covering on the ear cups and headband. After two years of daily use abuse, it flakes off. Like peeling skin.