i'm looking at purchasing a good pair of noise cancelling headphones and i've got two pairs in mind and its between the JVC HA-NC250 and the sennheiser pxc350, i was looking at the bose but their too expensive, i'm surprised at the great reviews that jvc are getting, i already have the sennheiser pxc250 but i want to upgrade them so any advice would be welcome thank you very much.