The speaker settings only apply to the 5.1 output; the digital output (which you have properly set to "normal") is passed directly from the disc to the output for the 990 to play with. With the 990 downstream of the 3910's 5.1 output, I'd recommend setting all speakers to large, the subwoofer to on, and leaving all channel levels and delay times "zero" on the 3910. That way, the 990 is the only unit that applies settings of these types.