Irrelevant.

The size of the music file has nothing to do with the volume of the music sound. What you are referring to should be different formats, such as: MP3 RM WMA. They have differences in sound quality.

The sound volume of the speaker has nothing to do with the USB flash drive, but is related to the original volume of the music stored in the USB flash drive. When the power amplifier and speakers are normal and all parameters are fixed, the music originally stored in the USB flash drive will sound louder when played; if the original sound is small, the sound will become quieter when played.