I'm upgrading from a stereo setup to a 5.1 setup and since you have a 5.1 setup perhaps you can answer these questions.

In my sound cards interface, I have the option of 3 different output modes, as seen in the threads subject. Is there a general consensus on which of those three is the best? I'm currently running 3.1, and when I set it to PCM, even 7.1 PCM, I cannot ping my center channel or subwoofer from the interface, but the receiver still plays through them like normal. Is this something to worry about? When I set it to the latter two output modes I CAN ping them from the sound cards interface.

Is PCM meant solely for 2 channel stereo? Are the other two modes better for anything beyond 2 channel?

Thanks much.