From the dispay of the 970 how can you tell if the Dolby Digital EX encoded source contains the extra back channel? I think the 970 will display 3/2.1 for both DD 5.1 and DD EX sources because the extra back channel is matrix and not discrete. The reason I ask is that DD EX is avialible from the surround modes on all DD 5.1 sources. Is there anything that indicates if the soundtrack contains the extra back channel?