Microphone jacks and built-in speakers are devices connected to an ADC and DAC, respectively for the input and output of audio.

话筒与内置扬声器分别是与adc和DAC相连的音频输入与输出设备。

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As a test, I downloaded files from HDtracks.com, an online retailer specializing in hi-res audio, plugged a device known as a digital-to-analog converter (DAC) into my computer and listened over earphones.

WSJ: Sonic Truth

Up until this week, this particular piece of circuitry was the title holder for "world's thinnest smartphone, " measuring in at 6.55mm thick. (The Alcatel Idol Ultra now claims this title at 6.45mm, although it's technically not on sale yet.) Despite the small package, it also professes to pack a hefty audio punch, boasting a pair of Beyerdynamic MMX 71 iE earphones and Cirrus Logic CS4398 DAC.

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