Methods and apparatus for calibrating an audio system including headset coupled to an electronic device via an audio dongle. In an example, a circuit configured to couple a Universal Serial Bus (USB) audio dongle with an audio circuit of an electronic device can include a first impedance configured to couple with a first audio channel of the audio circuit, a second impedance coupled in series with the first impedance and configured to couple with a second audio channel of the audio circuit, a third impedance coupled to a ground sense channel and to a node common to the first impedance and the second impedance, and a controller configured to initiate a first signal on the first channel, to monitor crosstalk of the first signal on the second audio channel and to adjust a setting of the third impedance to reduce the crosstalk.