WAV files sound awful on Micro SD

The WAV files I copied onto the Micro SD card sound awful.  When I copy the same WAV files onto the internal card, they sound just fine.  Also when I convert the WAV files to MP3 format and put those on the Micro SD card, they also sound just fine.  But WAV on on my Micro SD card - just horrible!  This is driving me crazy.  Is anyone else having this problem?

Most people don’t use WAV files. They convert to FLAC for the same quality, but half the file size.