Stereo in surface 45/46 , 47/48 and usb

I Would like I at the same time as working with stereo of these 3 channels in the GLD, but I cannot because the GLD has only 2 channels stereo of entrance. I can do to him routing of the work entrance 47/48 to a mono chanel like the 44 for example.

Sorry for my traduccion.

Greetings