The following represents my understanding of how the Outlaw 990 supports a 6.1 speaker configuration after talking with Scott last week. If I am incorrect in any way please let me know.

The most important fact was that the 990 cannot be configured to recognize 6.1. While the auto set-up can detect a single speaker, it does nothing with the data. This has several ramifications.

1) The 990 only supports 6.1 to the extent that a processing mode is itself 6.1. These include DD Surround EX or one of the DTS flavors ES-Matrix, ES-Discrete or DTS:Neo-6.

2) The DD IIx modes as implemented on the 990 do not support upconversion of a 5.1 signal to 6.1 (despite this being part of the DD IIx specifications on the Dolby site). My understanding per Scott this was that this was a limitation they ran into when developing the software for the 990. However, Scott then indicated that he thought that there typically was not a lot of difference in the content between the two rear channel bands, so using one of these two channels feed a single rear center might well prove acceptable.

3) If the 990 is fed a 7.1 analog signal, it cannot combine the two into a 6.1 output. Consequently, to support 6.1, you need to be able to configure the input device to output 6.1. If your analog source device cannot be configured to output 6.1, you may be able to use other workaround if that vendor supports them.

In terms of a work-around, I asked if I could use a Y connector to join the output signals of the 990 into a single output. He said no that this could harm the 990. I am not sure I understand why fully (so I invite Scott or others to post a more detailed explanation).

In general Scott seemed like Gonk seemed to favor DD IIx Movie over DD Surround EX for use when watching 5.1 content

Additional Notes:

Scott confirmed that the second entry on the surround format page (page 13) PL IIx MOVIE + DOLBY VS 5-SP WIDE is a not available. He said that on the 990 two types of post processing cannot be combined and that IIx is a post processing of DD-II.