For audio amplification, a class a amplifier can be either single-ended or push-pull.

对于音频放大，一个A类放大器可单端或推挽。

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And for people who use their voices a lot, like singers or professional speakers, get voice training and use an amplifier.

VOA: special.2009.09.02

You also get a small digital amplifier with a stereo headphone jack.

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Other new features include a new digital amplifier, a Bluetooth remote, and a settings memory to remember your source, volume and EQ levels for next time.

ENGADGET

Samsung's Vacuum Tube Soundbar (model HW-F750) resolves consumers' desire for pure power and warm, natural sound by integrating a vacuum tube amplifier into a soundbar for the first time.

ENGADGET: Samsung introduces its CES audio hardware, claims a world first