To provide an amplifier with a preamplifier circuit, a charging battery and a charging circuit, in which the charging circuit connected to the charging battery is not a cause to noise production and which provides excellent reproduction sound quality and continues sound reproduction even when a battery residual capacity of the charging battery is small.

A power supply circuit includes: a DC power supply output circuit connected to an AC power supply and outputting a DC voltage; the charging battery connected in parallel with an output of the DC power supply output circuit; and the charging circuit connected to the charging battery and a control circuit, the control circuit switches between the case of using an output of the DC power supply output circuit for a power supply output of the power supply circuit and the case of using an output of the charging battery for the power supply output of the power supply circuit depending on a charging state of the charging battery, and when the control circuit switches the power supply output of the power supply circuit from the output of the DC power supply output circuit into the output of the charging battery, the control circuit stops the operation of the charging circuit and predicts the charging state of the charging battery on the basis of an elapsed time from the switching time.

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