I've just bought a Marantz SR4300, and I'm very pleased with it. I have six speakers hooked up (L/C/R/SL/SB/SR), and they all work correctly in the 'setup' menu and surround modes etc. However, I can't get it to run DTS-ES with all six speakers. I am trying it with Gladiator (has DTS-ES on the box) and it refuses to turn on the surround back channel, no matter which mode I set the amp to. I have selected the 'DTS' audio channel from the DVD's audio menu, and the SR4300 selects 'DTS' mode, and lets me select 'DTS ES' but with only 5 speakers active. I tried a couple of DVD players but no luck. Any ideas?