Ok now for the minor techie stuff for Gonk...my system is pretty much configured the same except for adding the BDP93 and AE7000. This may be a grade school question that I've asked before but with the 990 when watching a BD, does it auto-magically assign the audio output based on the format of the disk? I ask because with each disk I played, the 990 only allows me to choose select audio formats.
When using the digital output, the BDP-93 should be set to output a bitstream. If you have it set to LPCM output, all you'll get is stereo. Either way, the Model 990 does have a limited set of options available to choose from depending on the input signal format. Dolby Digital 5.1 must be decoded as Dolby Digital, and in a 5.1 system there's nothing more really to do. DTS 5.1 must be decoded as DTS, again with no additional processing options because all speakers are already active. If you have a stereo sources (Dolby 2.0 or PCM stereo), then you may have the option of using Pro Logic II or DTS Neo:6 or 5 Stereo to expand that to 5.1 (which ones are available will depend on the format of the stereo source).
When using the analog output and the Model 990's 7.1 channel analog input, the Model 990 doesn't have any processing to do. The BDP-93 will decode and send the audio out in whatever number of channels are available. For a 5.1 system, you'd want to set the downmix to 5.1 for those times that you run into a 6.1 or 7.1 Blu-ray disc.