Specifically, I am wondering how 5.1 material sounds played through "matrix" and "non-matrix" 6.1/7.1 modes. Is it an improvement, or better to turn of the surround back speakers in 5.1 mode? I will be picking a 3802 up tomorrow. Since I just upgraded my center channel speaker, I was planning to use my older one as a rear center, but I've never used a 6.1 system before. In fact the only 6.1 software that I own is Gladiator, but I'm anxious to test it. Just wondering what your personal preferences are for this feature.