As Houghers points out, in addition to the handful of DTS-ES Discrete discs available (Lord of the Rings EE, Gladiator, and a few others) there are also three matrix decoding modes available in the 970 that can generate surround back data: Pro Logic IIx (which can be used with PCM stereo, Dolby Digital 2.0, Dolby Digital 5.1, and I believe DTS 5.1 as well), DTS NEO:6 (which can be used with DTS 5.1), and Dolby Digital EX (which can be used with Dolby Digital 5.1). To connect a single surround back speaker, you will connect to the left surround back pre-amp output channel and set the 970's surround back to "LB".