Kwok, yes I tried a Y cable.

I am still evaluating different modes, but there does seem to be a difference in surround modes. In some cases, a resonable one.

Keep in mind, I am sure this is not an Outlaw 990 only thing.

Obviously, the more "reprocessing" you have to do, the less clean the outcome. There is no such thing as getting extra from nothing (pseudo 7.1 from 5.1), there is always a cost..

What would be best is a world full of true 7.1 material in the first place..