In this paper, we demonstrate a recently proposed security technique for mixed-signal circuits in the context of a real application. The security technique, called MixLock, is based on logic locking of the digital section of the mixed-signal circuit and can be used as a countermeasure for reverse engineering and counterfeiting. We demonstrate MixLock in an audio application, where the underlying Σ∆ ADC that digitizes the audio input is locked. We show the effect that locking has on the recorded audio quality based on a metric that counts the resultant glitches per second and by also providing a link where the interested reader can download and listen to output audio samples for locked and unlocked versions of the Σ∆ ADC.