Apple and Samsung are already bitter enemies in the smartphone world, and headphones may be their next battleground. Samsung has just launched its Level family of high-end audio products in the United States. The lineup, first introduced in April, is led by Level Over, a $349.99 pair of over-ear Bluetooth headphones with active noise cancellation, NFC pairing, and what Samsung claims is powerful, clear, sharp sound. They can also be plugged in thanks to a detachable audio cable (with microphone and remote controls for your smartphone). Samsung targets big audio spenders