So a few days ago we checked out the new Sennheiser HD 350BT’s… but today we’re checking out the upgraded Sennheiser HD 450BT’s. Now obviously one of the main differences between these two headphones is that the 450BT’s have active noise cancellation. But the HD 450 BT’s are also replacing the 4.50BTNC’s… So lets see if its worth upgrading whether cause you already have the 4.50BTNC’s or if you just want save some money and go with the HD 350BT’s.