When transferring your media files to the Sony PSP you can easily increase the volume using Digital Media Converter Pro. Before starting the conversion, on the menu select Tools >> Video Effects, select 'Change Volume Level' and use the slider to increase the volume. You can preview the volume levels to make sure there is no distortion, then proceed with your conversion. When the conversion is complete click Tools >> Export to PSP and Digital Media Converter will transfer your converted files to your PSP.