If something is broadcast in 5.1, the 1050 will automatically detect it and switch to that mode. You should notice the change on the front panel of the 1050.

I don't have Digital Cable, but I do have Dishnetwork. I have one HBO that is broadcast in 5.1 all the time. The rest are all Pro Logic. Other than the pay-per-view channels, that's the only one that does broadcast in 5.1 that I know of.