Some square dance stereos are plugged in with a USB flash drive If it's a memory card with a card reader can it be done

Can.

Memory card plus card reader is actually formed a U disk.

In addition, this kind of audio can be inserted into the U disk, generally can also be directly inserted into the memory card, in the audio on the USB port near the look, not far from the USB port, there should be a TF card, SD card slot.