Headphone playback devices can include a cable assembly including a plurality of conductors extending between a first earpiece and a second earpiece. The cable assembly includes a jacket, a power conductor disposed within the jacket and coupled between a power source in the first earpiece and a wireless transceiver in the second earpiece. The cable assembly further includes a microphone conductor at least partially disposed within the jacket and coupled to a microphone in one of the earpieces. A shield is at least partially disposed between the power conductor and the microphone conductor to reduce electromagnetic interference between the two.