You have gotten to the aspect of choosing what sc you want to assign to what output .
i have used my SB card ,by itself, in conjuction with a usb sc ,on every version of Cross from 1.25 demo to 1.6, have tested my setup and have given feed back on the discrepencies on my setup on each
have help neumerous menbers with ion and sc set up . it can be done
you can check postings along the line of ion sc setup ,dual sc set up
trying to help
in the drop down menues check what sc output to use for each,.found that the outputs from the sb multi channel sc may get backwards in the labeling, meaning that the listing of what output (fr r/l ,rear r/f, side r/l. ) might not sort out the same,had to check 3/4 from sb and was coming out of 5/6.also put sb sc in the 4 channel mode