Electronic devices and accessories such as headsets for electronic devices are provided. A microphone may be included in an accessory to capture sound for an associated electronic device. Buttons and other user interfaces may be included in the accessories. An accessory may have an audio plug that connects to a mating audio jack in an electronic device, thereby establishing a wired communications path between the accessory and the electronic device. Path configuration circuitry may be used to selectively configure the path between the electronic device and accessory to support different operational modes. Analog audio lines in the wired path may convey left and right channel analog audio channels. When it is desired to convey power over the wired path, one of the analog audio channel lines may be converted to a power line. Audio functionality may be retained by simultaneously converting a unidirectional line into a bidirectional line using hybrids.