I run a reasonably high end system: Separate pre/power amp, KEF reference floorstanders, 2 x KEF 30B subs, Yamaha DSPE 800 processor. Viewing is all live rock concerts/music DVD with the volume well up. Can anyone tell me why when watching in 2 channel stereo I can hear the bass to an optimum level - not overpowering, but seamless in the rest of the sound & can feel a lovely rumble through the floorboards. Switch to DTS or DD though & the bass seems to disappear/get lost, so much so that I end up changing back to stereo. Any ideas as to the problem?