PCM stereo out of 5 channels? makes no sense

[Slec]

This makes little to no sense so i'm hoping someone can enlighten me. When watching/listening to Dave & Tim :Radio City Music and flipping between the Stereo PCM Track (24bit/48kHz) and the TrueHD track (24bit/96Khz) I notice a difference. its similar to what DaVID Boulet described in here:
https://forum.blu-ray.com/showthread...+TrueHD+Stereo

The PCM track seems to have more depth to it and in fact it's coming out of all 5 speakers. A bit different from stereo and I'm not complaining but I am curious. Most of the sound comes from the fronts, but sound does travel to the surrounds as you'd expect. The Dolby TrueHD track seems "smoothed" or not as hot as the PCM track. Although it is the simplest explanation, I don't think the Onkyo 605 will take a 2.0 track and convert to 5.1. Anyone have any ideas or also experience this? The above thread really didn't solve anything and got too far away from the topic at issue.

Thanks