Hi community, I simply don't know what to do anymore, I own an iMac on high Sierra, my babyface and total mix works great but when I wear headphones and use the output on the side of the hardware it only gives me mono signal.

when I open total mix and use the pan all the way to the right for example, I see the main out sending the music to the right however on my headphone I still hear music on both sides.  mono button is not active.

I tried using other headphones, I updated the drivers, I tried restarting, reseting Totalmix, I don't know what else to do, please help me here, I`ll have to sell my babyface if I don't find a solution.

any suggestions from anybody ?
thank you