DSD files are not loud as "normal flac" files

Hi guys,

i am running raspberry 4 with hifiberry dac+ pro. Connected to a jbs audio atom headphone amplifier. System is max2play with LMS.
Music is stored as flac and dsd on a ssd.

So my problem is that dsd files aren`t so loud as flac files. I need to turn the volume a quater higher to get the same volume as flac files.

Can somebody help me?

Greetings Daniel