If you get the same issue in mono, there could be a hardware issue.
Have you swapped cables as well? It might be related to a defective cord.
HTH
Just for clarification purposes, what are you running the XLR main outs into?
Swapped and changed cable.
the wires are going into a mixer, I tried on a sound card and another mixer....
...and what happened? Same thing? Something changed?
...and what happened? Same thing? Something changed?
Should be the same in mono but what the heck, did you try different rigs when testing the mixer / soundcard?
Well, if you swapped the cables and still get the same results the problem must be after the cables, otherwise left and right channel volumes would have swapped too. It's extremely unlikely that the two mixers and your soundcard show the same failure though. What are you listening through. Could that be damaged?
Yeah, i try different rigs\efx\patches and performance mode\browser mode etc..
It sounds like a hardware problem 
Is the Panorama control panned toward one side?
Yeah, i try different rigs\efx\patches and performance mode\browser mode etc..
It sounds like a hardware problem
Looking that way, I would make a backup to flashdrive and then system reset. If there still is a difference between the two then open a support ticket.
Is the Panorama control panned toward one side?
No Panorama, the problem affects only the XLR out, the jack out work at the same volume.
It's time to try a system reset...
I think it's time to contact support though system reset can't hurt.
