When I had Cable, and listend to Music Choice channels (via toslink), I would only be able to listen with the 990 set to "Upsample".

If I put it on Stereo, Bass is the only sounds that would be produced and booming. If I went through the dolby settings, I would get normal sound, though through channels that I did not want sound from (center).

I switched to DirecTV, and with the XM channels, I have the same problem via the same toslink cable and into the same 990 input. Quite loud and alarming when you try to cycle through the stereo settings.