I'm looking at Sony MDR7506 and MDRV600 headphones to use when im out with my portable rig. And obviously use monitors for the final mixdown!!! ha I was at guitar center they are both $100 and from what it seems is that the v600 just fold up? Is that the main difference, I think the frequency might be a tad difference but not too much. But if there is really no difference I'd like to get the V600's becuase they fold up nice and compact. I've read a lot about the 7506 but havnt heard much of the v600. I tried on the HD280's at GC but I felt the Sony ones felt a lot more comfortable and since all 3 of these cans cost $100 probably isnt much of a difference in sound quality.. I would think.