Actually, there is some information lost using the 6 channel direct. When the subwoofer channel contains information with a frequency over 120 Hz, it is filtered out by a low pass filter on that channel. It isn't redirected anywhere.

The filter works quite well. Before my 950 showed up last week, I hooked up my bass guitar rig, which is full-range, in place of the sub. I had a Kenwood 409 which is a true pass through on the 6 channel direct. I have a DVD-A player but I think the "lack of standardized" mixing exists in both formats. Reviewing the "Toy Matinee" DVD-A a little yielded significant info above the bass. The first track has snare drum early reflection or gated reverb in the "sub" channel.