Stereo Bluetooth headsets are often exercises in compromise: to be discreet they have to sacrifice sound quality, and to achieve sound quality they're often as large as the largest headphones. Jabra's Halo is different: they use flat-panel, over-ear drivers that should deliver more power without being ungainly. Combined with a stealth microphone and controls, it should in theory be the perfect mix. In our Halo review, we hope to discover if the set is a jack of all trades or a master of none.