Abstract: A charging case for a pair of wireless earphones comprising: a housing having a peripheral wall that defines a shell; a frame insert coupled to the housing and extending into the shell, the frame insert having one or more insert walls that define first and second pockets sized and shaped to accept first and second wireless earphones, respectively, wherein the one or more insert walls cooperate with the housing primary wall to define a sealed chamber within the charging case; a lid coupled to the housing and operable between a closed position in which the lid covers the first and second pockets and an open position in which the first and second pockets are exposed; a speaker module disposed within the sealed chamber, the speaker module comprising an audio driver having a diaphragm that separates a front volume of the audio driver from a back volume of the audio driver and a speaker vent disposed within the back volume; one or more first openings formed through the peripheral wall and opening into the front vol

Abstract: A method for operating an audio system having multiple Class D audio amplifiers is described. An external oscillatory signal is coupled to the amplifiers, such that the switching frequencies of both of the amplifiers align with (e.g., are directly set to) a frequency of the external signal. An input level associated with an audio signal that is being amplified is detected, and the detected input level is compared to a threshold. When the comparison indicates that the input level is below a lower threshold, the frequency of the external oscillatory signal is raised, and when the comparison indicates that the input level is above an upper threshold, the frequency of the external oscillatory signal is lowered. Other embodiments are also described and claimed.