The external sound card is generally USB interface. It is powered by USB interface. Computer USB ports are 5V voltage, 500mA current. If you do not use the USB interface of the computer for power supply, you can also use the mobile phone charger for power supply, as long as the output of the charger is 5V voltage, greater than or equal to 500 mA current can normally power the external sound card.
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If you don't have a charging port for your phone, look for something with a power converter
You mean passive sound. No sound card needs to be charged separately. Nowadays, electronic devices are not deliberately charged for the first 12 hours