I assume these are movies with DTS 5.1 tracks, right? You pick the DTS track on the DVD and the 990 detects the DTS bitstream and engages DTS, but only the center channel is active? I've listened to a number of DTS tracks and not experienced this. Somebody else may have some thoughts on this, but unless something pops up here tonight or tomorrow you might give Outlaw support a call and kick it around with them a bit.