Matrix processing to expand 5.1 sources to 7.1 is a weakness in current Blu-ray offerings, at least as far as I am aware. I haven't heard anything about the BD55 or S550 offering any sort of internal solutions to expand 5.1 to 7.1. I've also not seen much attention paid to 6.1 setups with players' multichannel analog outputs. And since 7.1 tracks are still pretty spotty for DTS-HD, TrueHD, and multichannel PCM tracks (the latter of which has largely disappeared from new releases), that is something that manufacturers ought to start thinking about.

On page 12 of the BD55 manual, it shows how to hook up the unit for 7.1 audio. Once you activate the unit for 7ch, it configures the normal L/R outputs as the L/R Back Surrounds. So, if you are playing a 7.1 soundtrack the Backs should then be active.

Most of us with just 5.1 systems will use the 2ch(Downmix) + 5.1ch configuration.

So, the question now is:
If I configure the BD55 for 7ch mode, run all seven cables into the 990, and the 990 only has 5.1 speakers configured, will the 990 downmix the 7.1 inputs to the 5.1 speakers configuration?

So it looks like we have 2 situations here with using the analog out of the newer blu-ray players:

1) 7.1 channel out w/7.1 speakers, but only 5.1 material sent.
2) 7.1 channel out w/5.1 speakers, but 7.1 material sent.

So the $64K question is how do players that do the processing, handle these situations? My situation is that I have really come to enjoy my rear speakers and don't want to "y" connect them to the side channels if only 5.1 material is available. That is what I did to play my SACD's when I used to listen to all 3 of them :^)

Like Gonk, I don't believe that the players have advanced this far yet with the processing to simulate or deal with these two issues. I guess I don't know enough about the 997 to see how it would deal with this either.

(sigh) isn't this hobby wonderful?

If you only have a 5.1 setup, the situation is simple: don't connect the rear surrounds, and tell the player that you only have a 5.1 speaker setup. The player should downmix 7.1 tracks to 5.1.

The real question here is what can be done when the system is 7.1, the player is connected via 7.1 analog, and the source track is only 5.1. The hook-up scheme that Lee mentions for the BD55 doesn't address this aspect. It is just a workaround for the fact that they didn't build in a dedicated 7.1 output and had to take over the stereo output to get the extra two channels. I couldn't find anything in the BD55 manual about processing that would achieve any sort of matrix processing to expand 5.1 to 7.1.

For what it's worth, this shouldn't be an issue when using the HDMI audio output with a reasonably current receiver or processor. The 997 should be able to provide Pro Logic IIx processing to expand a 5.1 track (be it TrueHD, DTS-HD MA, or multichannel PCM) to 7.1 just like the 990 does now with 5.1 sources.

The workaround on the Pannys has been to lower the other speaker levels in the player's speaker setup menu, since there is no way to adjust the sub settings louder in the same menu. Usually a -3 or -4 setting should do it.