I cannot hear my bandmates properly

[Schmidl]

Hi, my Band tried to start a new Session today, 
but I couldn't hear them properly. Only when I crank up the Headphones to max, I heard a little. 
They could hear me perfectly. 
About a year ago when we did it the last time there was No such problem. 

I am using a Behringer UMC 1820. 
Driver is installed and configured. 
DIM is deactivated. 

Any ideas anyone?

Thanks a lot. 

Dan