A method and circuit is disclosed for diminishing the DC offset or AC unbalance in an AC load driven by a phase control switch type controller. Information indicative of the user’s competency level and learning history is obtained using the target objects, and the threshold criteria defined by the provisioning rules is compared with the information indicative of the user’s competency level and learning history. Based on feedback from use with a given patient, the values are set to better optimize signal-to-noise ratio, off-time, tracking accuracy or other consideration. A user interface on the housing has different illumination colors respectively corresponding to different operation modes of the audio player.