Is there any reason why my AVR300 cannot play the DTS-ES Discrete soundtrack of a DVD when configured with only 5-speakers (front/center/rear) i.e. no Surround-Back speakers? I only hear a faint noise from the speakers. I previously posted this under the v2.84 software update thread, but this is annoying me a bit now... shouldn't the AVR300 play the DTS-compatible portion from the DTS-ES Discrete sound track when only configured with 5 speakers? At the moment, I can only play the DTS-ES soundtrack if I enable the SurrBack speakers in the menu (even if I don't actually have any installed/connected)... is this a limitation of other amps as well??