Has anyone used the digital output on the 990? With a 2 channel source such as CD, I assume it outputs the same 2 channel PCM signal, with volume/tone control and bass management. But how about a 5.1 source such as DVD? What goes out the 990's digital output in that case -- the same 5.1 signal after DSP, or simply front left and front right in PCM, or downmixed left and right in PCM? Thank you.