NEO:6 used to be limited to two-channel sources, but it wasn't able to compete well with Pro Logic IIx that way (since PLIIx can extend 5.1 material to 6.1/7.1) and it was being used in the background anyway as "DTS ES Matrix." By the time Outlaw shipped the 990, DTS had changed their standard for DTS ES and NEO:6 so that NEO:6 can be applied to multichannel sources to generate a surround back signal. There are some DTS-ES Discrete discs (Lord of the Rings EE being very notable examples along with Gladiator; Star Wars only uses Dolby Digital EX); those discs contain flags that automatically enable DTS-ES decoding to properly extract the surround back signal. Since no DVD players have offered 7.1 analog outputs (even the new HD-DVD players don't, although they should), DVD players have never included DTS ES or Dolby EX decoders - you must pass the digital bitstream unaltered to your receiver or processor.

The 990 will auto-detect any flagged DTS-ES or Dolby Digital EX content and process it as required by the flag. DTS has been pretty consistent about this from the beginning of DTS-ES's life, while Dolby's approach to the mastering of EX flags in soundtracks has been a slow evolution - early EX discs weren't even identified as such in software or on the packaging, and there are still newer discs that don't use the flag. Most Dolby EX discs and all DTS ES discs (at least all the ES discs I've seen) are flagged, and the 990 will obey those flags automatically. For unflagged Dolby Digital EX discs, the 990 will assume it is a Dolby Digital 5.1 soundtrack and treat it just as it would any other track - which in my case means applying Pro Logic IIx processing. Star Wars discs typically don't seem to include the flags, since I haven't had Dolby EX override my PLIIx preference with them.