You do not need to bypass the 990. A turntable would be connected to the Phono input, and you would want to use either Stereo, Upsample, or Bypass mode (all selectable with the Stereo button on the remote). A CD player would either be connected with analog audio cables or a digital audio cable, and in either case the Stereo button should allow you to select any of the same modes. When playing a DVD's Dolby Digitla track, which may or may not be a multichannel signal, you would need to use the Dolby button to scroll through to a "Stereo" mode I believe. For Dolby 2.0 tracks, that will be the same as "Dolby Digital" mode (decoded stereo, no other processing). For Dolby 5.1 tracks, that will be a downmixed stereo signal.