AA, possibly bigjohn is referring to the "Dialog Enhance" feature as described(superficially)on page 59 of your manual. It only mentions T-D mode and isn't clear if it's otherwise available. I'd guess that on the center channel it boosts the formant frequencies(about 1-4KHz)that give speech intelligibility and probabably it raises the center channel volume a bit too. If it is available you could try it for speech, although something like that wouldn't be very good for music.

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Enjoy the music, not the equipment.